







Class _ilILlLLQ_ 

Book_ > v' ^ 5 

Copyright ^ 0 __ 

COPYRIGHT DEPOSIT. 


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AND DIE DESIGN FOE 
BEGINNERS 


A PRACTICAL HANDBOOK FOR THE BEGINNER IN THE FIELDS 
OF TOOL DESIGN, DIE MAKING, AND METAL STAMP¬ 
ING, WITH TYPICAL PROBLEMS CARE¬ 
FULLY ANALYZED 


FRANK E. SHAILOR 

Ti 


MECHANICAL ENGINEER 

GENERAL MANAGER, DETROIT WELDING AND MANUFACTURING COMPANY 


ILLUSTRATED 


AMERICAN TECHNICAL SOCIETY 
CHICAGO, U. S. A. 

' 1917 






COPYRIGHT, 1917, BY 

AMERICAN TECHNICAL SOCIETY 


COPYRIGHTED IN GREAT BRITAIN 
ALL RIGHTS RESERVED 


APR -61917 

• * v 


©O.A457846 
"Vt^> l , 



INTRODUCTION 



OTHING has been more influential in the development of 


1 1 modern shop practice than the mechanical process called 
“tooling up”. Time was when each piece of work was treated as 
a whole and built from start to finish before any other piece of work 
was taken up. Gradually things were worked out in multiple and 
the complete device was finally assembled in tens or hundreds. 

<1 Today, for any job of sufficient size, the design of the device is first 
worked out in detail, and possibly an experimental machine built. 
Perhaps many changes will be made in this trial machine, but when 
the design has been approved, the working drawings are turned 
over to an expert tool designer to work out the most economical 
method of manufacturing the device in large quantities. The tool 
designer studies the drawings and lays out his work with extreme 
care. He calls for a jig here, a die for a stamping there; he designs 
what seem like innumerable fixtures for the various processes of 
the job and gives instructions to his men how to make these appli¬ 
ances. After what might be considered a long and expensive 
process, the “tooling up” is done, and, with his well-equipped machine 
shop, the manufacturer is now prepared to turn out the parts of 
this particular device in thousands and ten-thousands. Every 
part is so built that it exactly fits into the whole without a break, 
and the assembling of the parts is the last step in this series of 
operations which make up modern production manufacturing. 

<J The author of this little work is a skilled tool designer and speaks 
from a long experience in this field. He takes several typical 
examples and carries out carefully the various steps, from receiving 
the plans to the completion of the job. The publishers feel that 
this book is a worthy contribution to technical literature and hope 
that it will prove of distinct value to the trained man as well as 
to those who desire merely to keep up with the times. 



ROTARY SURFACE GRINDER,GRINDING HIGH-CARBON STEEL GEARS 

Courtesy of Jleald Machine Company , Worcester, Massachusetts 
















CONTENTS 


PART I—TOOL DESIGN 

SELECTION OF TYPE OF TOOLS 

PAGE 

Tools for production of flatiron. 1 

Method of finishing flatiron base. 1 

Drilling. 5 

Turning special bolt. 6 

Forming flatiron handle bracket. G 

Pressing flatiron top. S 

Piercing die. 12 

Requisites of designer. 13 

i 

PUNCHES AND DIES 

\ 

Blanking. 13 

Functions. 13 

Piercing-and-blanking die. 13 

Sub-press die. 16 

Combination die. 17 

Drawing and forming. 10 

Simple drawing die. 19 

Blanking-and-drawing die. 20 

Deep drawing die. 2G 

Shaving die. 27 

Embossing die... 30 

Extruding die. . v<. 30 

Forming die. 31 

JIGS AND FIXTURES 

Purposes.35 

Drilling fixtures. 35 

Proper relation of operations. 38 

Essentials in design.-. 39 

Devices for rapid operation. 39 

Boring and milling jigs. 


43 






























CONTENTS 


GAGES 

PAGE 

Classification and usage. 44 

Bench micrometer. 49 

SUCCESSFUL DESIGNING 

Problem of sequence of operations. 49 

Manner of holding work. 51 

Method of machining. 54 

Conditions for accuracy. 55 

Outlining methods. 56 

Design of product. 57 

Collaboration. 58 

Observation. 59 

PART II—DIES AND SHEET-METAL STAMPING 

BLANKING AND SHEARING TYPES 

Making simple punch and die. 2 

Size factor. 2 

Sequence of operations. 3 

Question of steel. 7 

Preparing die block. 8 

Laying out die. 10 

Shaping of die. 11 

Hardening of die. 15 

Finishing of die. 16 

Laying out punch. 16 

Forming of punch. 17 

Die shoe. 20 

Sub-press dies. 20 

Typical features. 20 

Making press body. .. 22 

Making plunger. 24 

Making small parts. 25 

Use of special cutters. 27 

Fitting piercing punches and dies. 28 

Placing round holes. 29 

Assembling parts. 31 

Sectional dies. 32 

Advantages.32 



































CONTENTS 


Sectional dies (continued) PAOE 

Laying out die. 32 

Shaping of die. 33 

Construction requirements. 34 

Making of die. 36 

Attaching piercing punches. 41 

Making blanking punch. 42 

Gang dies. 44 

Accuracy required in making. 44 

Approved method of making. 46 

Shearing dies. 51 

Two-punch principle. 51 

Making lower punch. 54 

Making upper punch. 57 

DRAWING AND FORMING TYPES 

Drawing dies. 59 

Finding size of blank. 59 

Types of die. 60 

Making combination type. .. ). 60 

Operation points. .. 61 

Method of making. 62 

Forming dies. 65 

Method of making. 65 

Embossing dies. 65 

Embossing. 65 

Die sinking. 66 

Jewelry dies. 68 

Fluid dies. 68 

Usage. 68 

Operation of fluid die. 68 

Substitute processes. 70 

Forming of die. 

Cutting design.. 74 

Drop-forging dies.. • • • 76 

Typical operation. 76 

Methods for saving material. 78 

Shaping die block. 79 

Recessing of die. 82 

Completion of die. 85 

Dies for trimming. 86 









































INGERSOLL 72-INCH FOUR-HEAD MILLING MACHINE MILLING HEAVY CASTINGS 

Courtesy of Ingersoil Milling Machine Company, Rockford, Illinois 





















( 


PART I 

TOOL DESIGN 


TYPES OF TOOLS 

Salient Features. The purpose of this article is to set forth 
the most modern design of tools generally used, such as jigs, fix¬ 
tures, punches and dies, etc., and why they are used, together with 
the degree of accuracy that may be expected in the manufactured 
article when made by these tools in the hands of an unskilled operator. 
There is such a vast difference in the methods and the degrees of 
accuracy required in the manufacture of harvesting machinery 
and of watches, that it precludes all possibility of establishing a 
standard design of tools. However, by closely studying the designs 
and the reasons for employing certain tools for certain operations, 
one will be able to decide which tools are best adapted for the vari¬ 
ous operations on the contemplated article of manufacture. 

SELECTION OF TYPE 

Tools for Production of Flatiron. Before taking up the study 
of the various designs of the many different tools, it is best that we 
first understand why certain tools are used, that is, why a jig is 
used instead of a punch and die, and vice versa. For an illustration, 
assume that we are about to design the tools to produce an electric 
flatiron, Fig. 1. This is admirably suited for our purpose, due to 
the fact that, in economically manufacturing this iron, there are 
employed blanking dies, drawing dies, forming dies, drill jigs, tapping 
fixtures, and milling fixtures. 

Production Basis. The first step from the designer’s point 
of view is to ascertain the number of irons to be manufactured 
yearly, as the production largely governs the design of tools. Assum¬ 
ing that the production will be 150,000 yearly, proceed to lay out 
expensive tools for rapid and economical manufacture. 

Method of Finishing Flatiron Base. The base a, Fig. 2, is of cast 
iron, and the drawing calls for finish on top and bottom. For 
machining the top and bottom of the base we have available four 



2 


TOOL DESIGN 


methods—turning; planing; grinding; or milling—the qualifications 
of which are as follows: 

(1) Turning the surfaces in a lathe would not be considered, 
due to the slowness of inserting the bases in the chuck, or of turning 
the fixture and removing it, with the additional loss of the operator’s 
time in waiting for the completion of the cut, but principally due 
to the poor surface produced by the circular cutting tool which would 
add to the polishing expense. 

(2) Planing the surfaces would be better, for we could make 
two fixtures for holding a number of bases, and, while the cut is being 
taken on one set of bases, the operator could unload and reload 



the second fixture. Planers, however, are seldom found in manu¬ 
facturing departments. Also the use of a single-pointed tool 
would not leave the desired surface when only one cut is taken. 

(3) Grinding has the disadvantages found in turning, namely, 
waiting for the completion of the cut, and the additional disad¬ 
vantage of the necessity of taking several cuts, for it is noticed 
that the drawing calls for a definite thickness of f inch. The cast¬ 
ings vary in thickness, and, unless we start the cut on the thickest 
castings, a broken wheel will result. 

(4) Milling has many advantages. First, there are a number 
of cutting points in the milling cutter. In addition, we can set 
and lock the cutter to a positive depth, insuring all bases being the 





















TOOL DESIGN 


o 

O 


same thickness regardless of variation in thickness when in the 
rough. Also, the finished surface of the base will be smoother 
than with planing or turning. 

Milling Fixtures. Having decided upon the milling cutter, 
our next problem is how to hold the bases, or which is the best type 
of milling fixture—largely governed by the type of milling machine 
we have at hand. If the miller is of the plain type, then we find 



Fig. 2. Parts of Flatiron 

that two milling fixtures are best adapted—one to be unloaded and 
loaded while the cut is being taken on a set of bases held in the 
other milling fixture, and the fixtures so designed as to be quickly 
attached on and detached from the miller. 

If we have at hand a milling machine having a circular milling 
attachment, we have the ideal method, for then the milling fixture 
can be designed as shown in the upper view, Fig. 3. In operation, 







































































4 


TOOL DESIGN 


the circular fixture a constantly revolves, as does the milling 
cutter b, and is so designed that as fast as the cutter lea's es the 




Fig. 3. View Showing Method of Finishing Polishing Surface of Iron. Lower Illustration 
Showing Jigs Used by Becker Milling Machine Company 

surface of a base the operator can readily remove the finished base 
and insert a rough casting without stopping the machine. This 






















































TOOL DESIGN 


5 


method proves to be the fastest because there is no lost time in 
stopping, starting, or changing the bases. 

The same line of reasoning must be followed in working out 
the details of the holding devices for the bases. Speed of operation 
and accuracy must be uppermost in the designer’s mind. The 
student must have in mind that although we have used only the base 
of the flatiron for an illustration, the methods, fixtures, and reason¬ 
ing are applicable to almost any flat work that is to be surfaced. 
Various designs of milling fixtures will be shown later. 

Drilling. Base . After milling the top and the bottom, the next 
operation on the flatiron base is drilling the two holes. For this 




Fig. 4. Set-Up for Turning Special Bolts 

operation a drill jig is used. L T nder the subsequent heading of Jigs 
and Fixtures are shown numerous types of jigs that could be used, 
but the open box jig, Fig. 64, used in conjunction with the multiple- 
spindle drill press is the most logical selection. There are no clamps 
or screws to operate, which means speed in operation. In order 
to further increase the speed of production it will be noted that the 
base rests on round cross-rods which prevents chips interfering and 




























0 


TOOL DESIGN 


eliminates the necessity of cleaning after each drilling operation, 
which is necessary on all other types of jigs. This particular type 
of jig is applicable only when all holes are drilled in the work at the 
same time, for then the work cannot shift. Accuracy closer than 
0.002 inch between the holes and the edge of the work cannot be 
expected. If the work is of a nature that a variation of inch is 
allowable, it would be cheaper to put V-spots in the pattern and drill 
the castings from the spots, eliminating the jigs entirely; this method 
should be practiced wherever feasible. 

Pressure Plate. The pressure plate b, Fig. 2, is machine drilled 
in the same manner as the base, using the same jigs and fixtures 
w here possible, even if necessary to design and make different holding 
fixtures and stops. 

Turning Special Bolt. The pressure bolt e, Fig. 2, being what 
is termed special, we have to design tools for it. These bolts can 

be made on the auto¬ 
matic screw machine, 
or on a hand-screw ma¬ 
chine, but in either case 
the hex rod should be 
turned to the screw' 
size, inch, starting 
from the end as shown 
at a, Fig. 4, and not 
with a crossbar tool as 
at b, Fig. 4; the reason 
being that the corners 
of the hex rod striking 
the bar tool w'ould cause 
the rod to jump and chatter. Also, it is difficult to maintain uniform 
diameters when using a crossbar tool, due to the spring of the rod. 

Forming Flatiron Handle Bracket. The handle bracket d, 
Fig. 2, is of sheet steel; the machining method in vogue before the 
advent of the punch and die was to clamp a number of flat rec¬ 
tangular pieces together, and, with a formed milling cutter, to mill 
the pieces on one edge, then on the other, and finally to drill the holes. 

Types of Dies. We now use punches and dies, described later, 
and the aim of the designer should be to complete as much of the 




Fig. 5. Types of Blanks for Handle Bracket 








TOOL DESIGN 


7 


work in one stroke as is practicable. In Figs. 16, 18, 19, 21, and 22 
are shown five different types of dies, any one of which would success¬ 
fully produce the bracket. If the plain type of blanking die shown 
in Fig. 16 were to be used, it would produce a blank as at a , Fig. 5, 
and it would mean that the bracket would have to go through another 
operation for piercing the holes. 

The punch and die, Fig. 18, sometimes called a follow die, also 
a pierce and blank, and a combination die, would produce a blank 
at each stroke as shown at b, Fig. 5. The objection found in using 
a combination punch and die is that the holes are pierced in one part 
of the strip of steel, then, when the strip is moved along until the 
pierced holes are. directly over the blanking die, in which position 
the blank is punched out, errors creep in, due to the strip stock not 



Fig. 6. Handle Bracket Shown in Three Stages of Development 


lying level on the surface of the die, and resulting in the holes being 
improperly located in the blank. 

The subpress die shown at Fig. 21 is used only for accurate 
work, due to its initial high cost. 

To produce our bracket, we will select the punch and die shown 
in Fig. 22—which, by the way, is really two punches—for the 
following reasons: By referring to d, Fig. 2, we note that the bracket 
is formed L-shape, with a rib between the two holes bb. This rib 
will change the original center distance between the holes bb, there¬ 
fore, it is best to pierce these holes after forming. The other advan¬ 
tages in using this type of die are that, instead of punching out the 
blank, as is the case with any other type of die, the surrounding 
stock is punched away, leaving the blank on the strip, Figs. 6 and > 
23, and a blank drops, completed, at each stroke of the press. This 
subject will be treated at length under Punches and Dies. 

Essential Reasoning. The student must study and become 
thoroughly conversant with each type of punch and die in order 
to follow out the following line of reasoning when designing tools 
for any article: 













8 


TOOL DESIGN 


(1) The plain blanking punch and die of the type shown in 
Fig. 16 should not be used, for it means several additional operations 
to complete the blank, also the tying up of several presses. 

(2) Neither the combination, Fig. 18, nor the subpress, Fig. 21, 
should be used, because trouble will be experienced in maintaining 
the proper center distance between the holes bb in forming the 
bracket. Also the blank would drop from the die only blanked 



Drhwing Die RTTncHED To Puticn Holder 



and pierced,- which would mean additional operations and presses 
to complete the forming operations. 

(3) The punch and die, Figs. 22 and 23, are selected because 
it requires but one operator and one press, and a complete bracket 
is produced every stroke as the result of progressive operation. 
This type of die, however, can only be used where a variation of 
0.005 to 0.010 inch is allowable. It could properly be called com¬ 
bination, for it blanks, pierces, forms, and cuts off. 

Pressing Flatiron Top. The flatiron top c, Fig. 2, is of sheet 
steel, and to produce it requires blanking, drawing, redrawing, 
trimming, and forming dies. To produce an irregular cup-shaped 
blank is one of the most difficult feats in punch-and-die work. 























































TOOL DESIGN 


9 


Finding Blank. The designer must work in conjunction with 
the tool-makers, and the drawing dies must be made first in order 
to find the blank, as the shop expression is. In other words, the 
profile of a blanking die cannot be designed, but must be found as 
in the following manner: Two pieces of steel of proper thickness 
are cut out exactly alike, 
of a shape that experience 
alone governs, for the de¬ 
signer must imagine about 
what shape the blank 
should be. These two 
pieces may be stamped 
A and A, and one piece 
formed by putting it 
through the drawing 
punches and dies, while 
the other blank is kept in 
its flat state. If too much 
stock, or not enough, has 
been left on the blank to 
produce the desired cut, 
or, if it is not the proper 
shape, the shape is changed 
and two more blanks are 
made exactly alike, 
stamped B and B, and 
one of these B blanks is 
also put through the draw¬ 
ing dies. When the de¬ 
sired shape is finally ob- Fig. 8. Flatiron Top in Process, (a) Faulty Construction; 
. (b) Blank as First Drawn; (c) Blank Properly Trimmed 

tamed, the mate to the 

formed blank which is accepted is used for the blanking die. 

Trimming. If the drawing punch and die, Fig. 7, were designed 
to draw the flatiron top or any cup complete at one draw, the edges 
of the top w r ould be irregular, as shown in a , Fig. 8, which would 
mean a slow facing operation. Therefore, the die is designed 
to draw the cup, say | of its depth, which makes the blank as shown 
at 6, Fig. 8; then a trimming die, Fig. 9, is made to trim the edge, 































10 


TOOL DESIGN 



leaving it as at c, Fig. 8. The punch a, Fig. 9, is fastened to the die 
shoe, which in turn is fastened to the bolster on the bed of a press, 

and the punch has a shaped 
top section to fit inside of 
the cup to act as a locator. 
This locator c is made de¬ 
tachable to permit of grind¬ 
ing the top face of the 
punch. The trimming 
punch and die are nothing 
more than a plain blanking 
punch and die and derive 
the name from the trim¬ 
ming operation on the cup. 

After the cup has been 
trimmed the |-inch margin 
all around the cup is uni¬ 
form in width and the edges 
are square. The cup is 
then pushed through a re¬ 
drawing die, as shown in 
the section at a, Fig. 10, producing the finished cup with parallel 
and straight edges as shown at ( b ) in the same figure. 


-KriIVES to Serrrrte the Pin 
TRIMMED RROM CuF> 



Fig. 9. Trimming Punch 


Cap Screws for 
Holdina Punch to Pam-, 



On Upward Stroke of Punch The 
Blank (a) Springs Open Enough 
To Catch on Corners which Strips 
Blank from Punch. 

Fig. 10. Section of Redrawing Die and Finished Top 



































































































































TOOL DESIGN 


11 


Extruding . When designing drawing dies to produce portions 
bulged from the central part of a cup, as/and g, Fig. 2, it is the best 
practice to design a sort of preparatory drawing die, that is, a die 
that will push out a surplus amount of stock but of a shape that is 
easy to draw, as shown in section at a , Fig. 11. The extruding 



Fig. 11. Part Section of Top of Flatiron Showing Design of Bulging Portions 


of metal from the center of a sheet causes that portion to stretch 
instead of draw, and, if there are comparatively sharp corners in 
the shape being extruded, the stock tears apart. For this reason 
a sufficient or even a surplus amount of stock is forced out, and 
then the forming punch and die, Fig. 12, are made to produce final 
shape on only the part 
/, Fig. 2, and to iron 
out any wrinkles or sur¬ 
plus stock that may have 
been caused by the pre¬ 
paratory bulging or draw¬ 
ing of the cup. 

The die, Fig. 12, 
shown in section, is made 
in the desired shape, and 
the punch is made the 
same shape, but smaller, 
for it is obvious that the 
metal to be formed must 
be between the punch and 
the die. The extruded 
portion g, Fig. 2, must be pierced with a small hole as in a, Fig. 13, 

before its final drawing, and the piercing die can be placed in 
the same die, Fig. 12, that finishes the part/, the object being to 

save an operation of handling the cup. If the extruded portion g , 
Fig. 2, is pierced while the top of the cup is flat, there are apt to 
be cracks in g when drawn to final shape, as shown in b , Fig. 13. 
















































12 


TOOL DESIGN 



Fig. 13. 


Sketch Showing Possible Tearing of Metal 
in Punching 


Sizing. The last drawing operation on the flatiron top is to 
draw and size the portion g, Fig. 2 (c). For this operation a sizing 

punch and die of the 
form shown in Fig. 14, is 
employed. 

Piercing Die. A pierc¬ 
ing die, Fig. 15, is em¬ 
ployed for the last opera¬ 
tion on the top, that is, for 
piercing the two holes hh, 
Fig. 2 (c), through which 
the electrodes are to come. 

It will be noted that 
the holes hh could be drilled 
in a jig. But there are many advantages in punching holes in thin 
stock, some of which are as follows: Both holes are pierced simul¬ 
taneously, insuring uniform center distances between holes, which 

would not be true if first 
one hole were drilled and 
then the next, because 
there is a slight differ¬ 
ence in the diameters of 
holes in bushings and in 
jigs and the drill used. 
Another advantage of 
punching is that in a 
drilled hole there always 
is a decided burr pro¬ 
truding from the bottom 
edge of the hole where 
the drill breaks through. 
Another reason why a 
piercing die is preferable 
to a drill jig is that thin 
stock does not drill sat • 


l 

m 

i 

i - 

PUNCt 

- r 

i Holder 

TTT" 

"T 1 

-H 

m 

ft 

_ m 

_L 

- 

i 

i 

m 

SI 

■ 



^ Punch Plate 



Fig. 14. Sizing Punch and Die for Flatiron Top 


isfactorily, due to the point of the drill being clear through the 
sheet stock before the body of the drill enters, which causes the 
drill to climb from the hole, producing an irregular hole. A final 














































































TOOL DESIGN 


13 


advantage is in the speed obtainable in inserting and removing 
the blank; there are no locking devices employed, as on jigs. 

Requisites of Designer. The foregoing is a bnef outline of 
how a designer must set about to design tools for any product. 
He must consider the ad¬ 
vantages of the various 
tools before he decides to 
use any particular one, for 
in some cases a tool not 
generally used for the class 
of work he may have at 
hand will prove to be best 
adapted for the job. After 
deciding which type of 
tool to use for a certain 
operation, the designer 
must then decide which 
particular style of that 
type of tool to use. In 

other words, the designer Fig 15 p iercin g Die for Two Holes in Flatiron Top 

must acquaint himself with 

every design of tool in general use and must cultivate the faculty 
of designing an original tool now and then to do some particular 
operation which could not be done satisfactorily with the tools of 
ordinary design. 

PUNCHES AND DIES 
BLANKING 

Functions. A punch and die, such as shown in Fig. 16, used 
to punch out from sheet stock the initial plain blank in Fig. 17, 
is called a blanking die. The plain blanking die has been elaborated 
upon so that the die can be made to do several operations prior 
to blanking, but as long as the desired blank is punched from the 
stock, regardless of prior operations on the blank, the die comes 
under the general classification of blanking dies. 

Piercing=and=BIanking Die. Fig. 18 shows what is known as 
a piercing-and-blanking die, also cut and follow, and combination 
die. With this type of die no very accurate work can be expected, 































14 


TOOL DESIGN 



Fig. 16. Typical Blanking Die 


for curvature in the sheet means varying distances between pierced 
holes. Another cause of inaccuracy is due to the fact that, in this 

instance, the two pierced 
holes in the stock are 
located over the blanking 
die by means of the pilots 
aa, and that these pilots 
are of necessity a trifle 
smaller in diameter than 
the holes, which allows 
variation in any direction. 
Also, curved or kinked 
stock straightens out when 
the face of the blanking 
punch comes in contact 
with it, causing the holes 
to become of greater dis¬ 
tance between centers, and 
distorted, due to pressure 
against the pilots. This die should be used only on work that 
does not require accuracy closer than 0.005 inch. 

Spring Stripper. Fig. 19 
shows the same design of 
die, with the addition of the 
spring stripper a attached to 
the punch plate. When the 
spring stripper comes in con¬ 
tact with curved stock on the 
face of the die, the spring 
pressure straightens the stock 
prior to piercing and blank¬ 
ing. Accuracy closer than 
0.003 inch cannot be ex¬ 
pected with this type of die. 
II ardened Bushings. 

When this type of die is to be employed for blanks over 2 inches 
long, the design shown in Fig. 20 should be used. The blanking 
section a is of tool steel and hardened, while the pierce section 




Fig. 17. 


Metal Sheet and Blank Cut from It 
by Blanking Die, Fig. 16 









































TOOL DESIGN 


15 


b is of machinery steel and has the holes bushed with hardened 
steel, the objects being: a saving of expensive tool steel; a smaller 
piece to harden, thereby lessening the chances of cracking when 
hardening; and removing the possibility of center distances changing. 
An added advantage is in the use of the bushing which can be easily 




Fig. IS. Typical Piercing-and-Blanking Die 


changed without annealing the die. The designer should call for 
bushed holes in all piercing-die holes where possible, whether of 
hardened tool steel or soft steel, for, if a different size hole is desired, 
all that is necessary is to make a new bushing. 

Punches. Piercing punches should be designed with heads. 
Fig. 15, as they are the easiest to make and cannot be pushed or 














































































































































































































































































16 


TOOL DESIGN 


pulled out of the punch plate. Using a set screw against the shank 
of the punch is not so good as it tends to tilt the punch. 




Subpress Die. The 

cross-section in Fig. 21 
shows a subpress die in 
its simplest construction. 
This type produces the 
most accurate work of 
any die in the blanking 
class. The designer 
should never call for a 
subpress die for work 
that does not require 
extreme accuracy; neither should he call for a piercing-and-blanking 
die when accuracy in the blank is required. When designing a 



Fig. 20. 


Sketch Illustrating Saving in Expensive Steel 
by Use of Bushings 
























































































































































































































































































TOOL DESIGN 


17 


subpress die, care must be exercised in having the necessary rigidity 
in the various members, especially in the guide pins aa. If there 
is considerable work to be made requiring subpress dies, then a 
suitable pattern should be designed and the bodies and base made 
of castings. 

In Tool-Making, Part III, Figs. 380, 381, and 382 show the three 
styles of subpress dies most generally used. 

Combination Die. In Fig. 22, herewith, is shown a peculiar 
type of die that is not old enough to enjoy a name but might properly 



Piercing Punches 
'cBldnking Punch 


Fig. 21. Section of Typical Subpress Die 


be termed a combination. The stripper is left out of the upper part 
to make the sketch clearer. This die differs from others in that 
there really is no die proper but it is made up of a number of punches. 
As previously stated, the stock is punched away, leaving the blank 
on the strip, in which position the blank can be handled for succes¬ 
sive operations, while in reality the blank is not handled at all. 

Elaborations. Fig. 23 shows this die elaborated to the extent 
of producing the profile which forms the blank, of piercing the holes, 
of cutting the blank from the strip, and of final-forming the blank to 
L-shape, all at one stroke of press. Of course, it is necessary at 




















































































































































































18 


TOOL DESIGN 



Upper Member For. Blemh/mc* 



Bower. Member Fee tehee To Die 5 hoe. 

Fig. 22. Combination Die 



Cut -off Punch■ 
Final Forming Punch ^ 



Pus\w View of Lower Member 

Forming Punchy 



Blanking Punchp 

t- -n-r ~~n 

j—u-1-J 


Piercing Punches\ 


T 

I' 

I' 

I' 

-Li. 


\ Side View of Lower Member 

Fig. 23. Elevation and Plan of Progressive Steps in Forming Finished Blank 


(, 

i 


















































































TOOL DESIGN 


19 



Fejhn View 




the start to move the strip four times, and 4 strokes of the press 
are required before a finished blank is severed from the strip, but 
thereafter, to the end of the strip, a piece, as shown in d, Fig. 2, is 
completed at each stroke. 

This type of die offers 
untold opportunities to the 
designer, for cross-slides 
for bending some partic¬ 
ular part can be added to 
the die, and the die can 
even be fitted with a tap¬ 
ping fixture actuated by 
gears driven by a rack 
attached to the punch 
plate, so that the desired 
blank can be blanked, 
formed, pierced, bent, 
tapped, cut off, and final- 
formed at each stroke of 
the press. One design of 
tapping fixture applicable 
to punch and dies is shown 
in Fig. 24; the vertical 
shaft a , to which the tap 
is attached, contains a 
long key by which the 
bevel gear rotates the tap 
shaft. 


Week Spring- 



Tnp Holder 


Fig. 24. 


Design of Tapping Fixture for Tapping 
Hole in Blank 




DRAWING AND FORMING 


Simple Drawing Die. Any type of die that performs a drawing 
operation is referred to as a drawing die, regardless of its construc¬ 
tion. Fig. 25 shows a drawing punch and die in its simplest form, 
producing only shallow cups, as in Fig. 2G, from blanks made from 
another die. The chief difference between this punch and die and 
the plain blanking type is that the punch, instead of fitting the die, 
is made smaller than the die by an amount equal to twice the thick¬ 
ness of the stock to be drawn. Also the sharp corners of the die 



























































20 


TOOL DESIGN 


are removed to allow the stock to slide freely from the flat state 
to cup shape, and to prevent scratching the blank. 

Fig. 27 shows types of 
cups that are formed by the 
drawing die in Fig. 28. When 
using this design of die, how¬ 
ever, the blanks must be 
punched out with another 
die. This die should not be 
designed for use except when 
a small quantity of cups are 
required. 

For producing the blanks 
seen in Fig. 29, the type of 
drawing die shown in its 
simplest form in Fig. 30 is 

Fig. 25. Simple Form of Drawing Punch and Die employed. This die also 



Nest To Locate 
Blattk 



Fig. 20. Typical Cups Formed by Drawing Die 




requires blanks previously punched from sheet stock. As is the 
case with all the foregoing drawing dies, this type should not 

be designed where rapid 
production or quality is 
required. 

Blanking = and=Draw- 
ing Die. We now come 
to that class of tools known 
as blanking-and-drawing 
dies. The designer is lim¬ 
ited somewhat in his selec¬ 
tion of a type of die that 
is best suited for the 
work, as he must design the dies that will be operative in the presses 
at hand. The die shown in Fig. 31 is designed for use in what is 



Fig. 27. Types of Cups Formed by Drawing 
Die, Fig. 28 






































































































































TOOL DESIGN 


21 


termed a single-action press, such as that in Fig. 32. In this case 
the press has only one crank on the drive shaft, and to that crank 
is attached the driving rod which actuates the ram, so that the ram 



Fig. 28. Drawing Die with Spring Stripper 


has but one action. The die, Fig. 31, produces any of the cups 
shown in Figs. 26, 27, and 29, and has the advantages over any 




Fig. 29. Typical Blanks Produced by Drawing Die, Fig. 30 


drawing die thus far shown of punching out its own blank and of 
drawing the blank to a cup at each stroke of the press, it will be 
noted that the die is somewhat complicated and that the blanking 

















































































































































































































































































22 


TOOL DESIGN 


punch is also the drawing die. This type of die should be designed 
for rapid production only when compelled to use a single-action 
punch press. 

Operation. In operation, the blanking punch d cuts out the 
blank and the blank is pinched between the angular faces of the 
lower stripper c and the blanking punch. As the punch continues 
to descend, the lower stripper descends also and the forming punch 



e forces the blank up into the drawing die, which is the recess / 
in d. The stroke of the ram is so adjusted that at the extreme point 
of the downward stroke the forming punch e presses the cup firmly 
against the face of the upper stripper a, while at the same time the 
back face of a is pressing firmly against the bottom of recess /. 

As the ram ascends, the lower stripper accompanies the blanking 
punch, that is, the stripper c, being actuated by heavy springs h, 



















































































































































TOOL DESIGN 


23 


ascends at the same speed as that of the blanking punch and strips 
the cup from the forming punch e. The lower stripper c, therefore, 
performs the double function of stripping the cup from the forming 
punch and of pressing the stock against the angular face of the blank- 
ing punch to prevent wrinkling the stock. It is obvious that if 
the flat blank were not held under pressure, the blank would wrinkle 
when it changes from a flat blank, say 6 inches in diameter, to a 


Fig. 31. Blanking-and-Drawing Dies Designed for Single-Action Press 

cup shape 3 inches in diameter. The designer must employ powerful 
springs to prevent wrinkling. Near the end of the upward stroke 
of the ram, the stripper shank i comes in contact with a cross-rod 
in the press called the knock-out rod, which pushes the stripper a 
down, leaving it in the position shown in Fig. 31. This causes 
the finished cup to drop from the drawing die to the face of the 
blanking die. 

















































































































































24 


TOOL DESIGN 


The operator must remove the cup from face of the die before 
blanking and drawing the next one—a somewhat slower operation 
than when this same die is used in a press of the inclinable type such 
as shown in Fig. 33; the press being tilted on a decided angle, the 
cups cannot remain on the face of the die, thus enabling the oper¬ 
ator to greatly increase the quantity of production. Therefore, the 
designer must learn which types of press he may have at his com¬ 
mand, and when designing dies of this character he must select 
the die best adapted and have it fitted to the press that will insure 

the most rapid production. The de¬ 
signer should also see that the plans 
from which the toolqnakers work con¬ 
tain notes calling for polished rounded 
corners on a drawing die, and for the 
sides of the drawing die and drawing 
punch to be highly polished. 

Double- Action Type. Fig. 34 
shows in section a drawing punch and 

die designed for a double-action press, 
♦ 

Fig. 35, and to produce the cups 
shown in Fig. 27. The shape of the 
end of the drawing punch a, Fig. 34, 
governs the shape of the bottom of 
the cup. The term double action means 
that there really are two strokes to 
the press. The drive shaft has three 
cranks or eccentrics, as shown en¬ 
larged in Fig. 36. The two end cranks 
are connected to the large ram, 
Fig. 35, to which is fastened the blanking punch 5, Fig. 34, 
while the central crank is connected to the smaller ram, Fig. 35, 
which slides inside the large ram. The position of the cranks is 
such that in operation the ram containing the blanking punch 
descends, and, before the blanking punch touches the stock to be 
punched, the inner ram containing the drawing punch a, Fig. 34, 
starts to descend. The rams are so adjusted that just as the blanking 
punch reaches its lowest point, which should be when the blank is 
firmly pressed against the face of the drawing die c, the drawing 



Fig. 32. Single-Action Press 
Courtesy of E. W. Bliss Company, 
New York City 




TOOL DESIGN 


25 


punch continues downward and pushes the blank down through 
the die. 

For producing the cups shown in Fig. 27, the die in Fig. 34 is 
the ideal one, due to its simplicity and speed of operation, for the 



Fig. 33. Inclinable Single-Action Press 
Courtesy of Toledo Machine and Tool Company, Toledo, Ohio 


blanks are pushed clear through the die. The double-action type 
of die, however, is not any better suited for those cups in Fig. 29 than 
the die for a single-action press shown at Fig. 31, for in using either 








26 


TOOL DESIGN 


type the cups would have to be removed from the top of the die 
unless the press were inclinable. 

Deep Drawing Die. The term deep drawing is applied to dies 
that are employed to produce long shells or deep cups, such as that 
in Fig. 37. These dies might properly be classed as redrawing dies. 
It is obvious that the shell in Fig. 37 could not be produced in a 

drawing die in one operation, 
for the diameter of the draw¬ 
ing punch would be so small 
relative to the draw that the 
punch would push through 
the blank. In other words, 
the pressure required to trans¬ 
form the large blank into a 
long slender tube, at one 
stroke, is greater than the 
pressure required to push the 
punch through the stock. 

To produce the shell in 
Fig. 37, there is required a 
series of redrawing dies such 
as that in Fig. 38, and as 
can best be understood by 
referring to the successive 
drawing operations indicated 
in Fig. 39. When a cup has 
passed through several re¬ 
drawing operations, the stock 
in the cup. becomes very hard 
and the cups must be an¬ 
nealed before further drawing. The cup in Fig. 39 would 
require possibly two annealing operations—the deeper the cup, 
the greater the number of draws and annealing operations. The 
dies should be designed for the successive operations in prac¬ 
tically the shapes shown by the dotted lines in Fig. 39, and, as in 
Fig. 40, should be provided with a plunger actuated by a powerful 
spring, to insure the cup being forced from the die, and also w T ith 
a close fitting stripper surrounding the punch, care being exercised 



Fig. 34. Drawing Punch and Die Designed 
for Double-Action Press 









































































































TOOL DESIGN 


27 


that the stripper for the punch is high enough from the face 
of the die to allow the blank to be readily removed from the die. 



Fig. 35. Double-Action Press 

Courtesy of Waterbury-Farrel Foundry and Machine Company, Waterbury, Connecticut 


Shaving Die. When a punch passes through the strip of stock 
to be punched, the blank punched out is really broken from the stock, 
rather than being cut apart, and this breaking leaves a ragged 
edge on the blank and in the hole in the stock. The thicker the stock, 






















28 


TOOL DESIGN 


the more pronounced this ragged edge is. Blanks punched from, 
say, J-inch sheet stock are decidedly tapering, as in Fig. 41. When 



Fig. 36. Crank Shaft of Double-Action Press 


punching cams, levers, eccen¬ 
trics, or small parts for type¬ 
writers, adding machines, cash 
registers, etc., where the action 
of the cams and levers must 
be smooth, a shaving die, 
shown in its simplest form in 
Fig. 42, is employed for finish¬ 
ing the blank. The blanking 
die is designed to punch the 
blank very close to the desired 



Fig. 37. Typical Deep Drawing 
Blank 



Fig. 38. Series of Redrawing Dies for Deep 
Drawing Work 


size or shape, leaving an allowance of only a few thousandths for 
shaving. In connection with such a piece as the eccentric washer, 
Fig. 43, the outer edge of which must be smooth, as it runs in a 

















































































































































































































TOOL DESIGN 


29 


bearing, the designer should employ the subpress die, Fig. 21, because 
this type of die produces the most uniform blanks. 

As a rule, the shaving die is not given clearance, as is the case 
with blanking dies, and, as the punch must fit the die very closely, 
it is the general practice to make the shaving die in accordance 




with subpress construction, which insures alignment of punch 
and die. The shaving die can be fitted with a close fitting spring 
stripper, as in Fig. 42, or the blanks can be pushed through, as desired. 
By making the die, say, 1 inch deep, and without clearance, and by 
keeping the die and blanks well lubricated, and pushing the blanks 































TOOL DESIGN 


30 

clear through, a highly polished edge is produced on the blank. The 
designer should bear the shaving die in mind and use it wherever 
feasible, for it is a very rapid method of producing pieces of 
uniform size. 

Embossing Die. Fig. 44 shows samples of ordinary embossing 
—though for heavy embossing, as at a , Fig. 44, a drop press is best 





-Punch Stripper 


r-u-t Die Stripper) 

^rAT — 7 *—~ 



Fig. 40. Punch and Die for Producing No. 2, Fig. 39 


suited. If the embossing desired is somewhat heavy and there is 
danger of springing the shaft of the punch press, and the designer 
must of necessity use a punch press, it is better to use a die of design 
such as that in Fig. 45, rather than to have the blow struck directly. 

Extruding Die. If a cartridge shell were filled with butter, 
and a lead pencil forced to the bottom of the shell, the butter would 
ooze or flow up the pencil. This holds true with metal; it is simply 
































































































TOOL DESIGN 


31 



Fig. 41. Blank Punched from 
Quarter-Inch Stock Show¬ 
ing Tapering Sides 


a matter of pressure. Small eyelets, hollow rivets, and thin tubes 
are economically made with extruding dies, such as in Figs. 46 
and 47. In operation, referring to Fig. 47, 
a punched washer of predetermined thick¬ 
ness is dropped into the recess of the 
die, and as the punch fits the recess there 
is only one path for the metal to flow in, 
and it is then simply a question of pres¬ 
sure. As it requires time for the 
metal to flow, the press must 
travel comparatively slow, and 
therefore hydraulic presses are 
used. If an extruding die were 
fitted to a punch press running 
at ordinary speed for blanking— 
about 100 revolutions per minute 
—it would be apt to break the 
shaft of the press, as there would 
be practically a direct blow. 

Another type of extruded work is 
shown at a, Fig. 46. This scheme 
is often employed where a tapped 
hole is desired in thin stock, as 
at b in the same figure. 

Forming Die. Fig. 48 shows 
a forming die in its simplest form. Form¬ 
ing dies can be made part of many dies 
that pierce and cut off, or, if the blank 
has straight sides as at a, Fig. 49, the 
stock can be purchased in the proper 
width, and by adding the forming die 



Fig. 42. Shaving Die 



Fig. 43. Blank for Eccentric 
Washer 



Fig. 44. Typical Examples of Embossing 



























































































































32 


TOOL DESIGN 





Fig. 46. Typical Extruding Die 


































































TOOL DESIGN 


33 


Washer from which 
Hollow Rivet is made 




Fig. 47. Operation of Extruding Dies 


Fig. 48. Simple Forming Dies 




Fig. 49. Piercing and Forming Die Work 








































































































































































































































































































































34 


TOOL DESIGN 


to the end of the piercing-and-blanking die, as shown in Fig. 49, 
the blank can be pierced, cut off, and formed. The designer should 
always bear in mind that the forming points in a punch and die may 

be changed from the posi¬ 
tion shown in Fig. 48, and 
that formed pieces, such as 
at a, Fig. 50, can be easily 
made in one stroke. 

Liquid Forming. Fig. 
51 shows a plain design of 
water forming die. The 
designer can elaborate upon 
this design and produce 
intricate forms, using water. 
The dies are designed in 
halves, one-half stationary, 
while the other half slides, 
being actuated by a lever 
that can be locked when the 
halves are firmly pressed 
together. In operation a 
drawn cup such as a, Fig. 52, 
is filled with water, the cup 
is inserted in the die and 
the halves of the die are 
closed and locked. The 
punch, which is attached 
to a drop hammer, fits the 
inside of the cup closely, 
and, as the hammer falls, 
the punch strikes the water, 
forcing the metal into all 
parts of the die. The object 
in making the dies in halves 
is to allow removing the 
blanks when they are formed 
to a larger diameter as in 6, 

Fig. 51. Design for Water Forming Die Fig. 52. 











































TOOL DESIGN 


35 


This same design of die can be used for thin stock when a spring 
rubber plug is employed. The rubber forces the thin metal walls 



"1^1 

V 

J 



Fig. 52. Water Forming Die and Formed Blank 


of the cup to all parts of the die, and as rubber assumes its original 
shape after pressure is released, it can be easily removed and used 
over and over. 


JIGS AND FIXTURES 

Purposes. The term jig is applied to a device designed to hold 
work while being machined, and to contain guides to govern the 
cutting tools. Jigs are divided into many classes, such as grinding, 
boring, turning, planing, milling, and drilling jigs. 

Drilling Fixtures. Extremely accurate work cannot be obtained 
in jigs for drilling because there must be a difference between the 
diameters of the bushing hole and the drill to be used, and this 
difference can be transferred to the work. In a, Fig. 53, is shown a 
drilling jig in its simplest form. 

The aim of the designer should be to design the jigs as nearly 
foolproof as possible, for in the use of jigs there must be locating 
points to position the work and locking devices for.holding the work 























































































36 


TOOL DESIGN 


o o 





Fig. 54. Drilling Jig with V-Rest for 
Centering Work 


in position. Should a jig be 
made where the successful 
duplication of work is left 
partly dependent upon the 
care of an unskilled operator, 
there is the possibility of 
many ruined pieces, due to 
the operator’s failure through 
lack of interest to properly 
clean the locating points, to 
remove chips from corners, 
or to properly secure the 
work in the jig. Therefore, 
all jigs should be designed in 
such a manner that the per¬ 
sonal element is reduced to 
the minimum. 

V-Type Jig. The fea¬ 
ture of the simple design of 
jig in Fig. 54 is the V-shaped 
portion for centrally locating 
a round piece of work. When 
a lubricant is used in the 
machining operation the chips 
stick to the angular sides, 
but to reduce this danger to 
the minimum, the V is 
relieved, as at a, Fig. 54. 
In Fig. 55 we have the same 
V feature but of improved 
design intended to mechan¬ 
ically locate and hold. It is 
noted that there are no lock¬ 
ing screws, cams, or adjust¬ 
ing screws for the operator to 
forget, and that all that is 
necessary is for the operator 
to insert the piece of work 
















































































































































































































































TOOL DESIGN 


37 


and to close the cover. This, in its simplest form, is what is known 
as foolproof, and the designer must design the tool at hand to operate 
mechanically as nearly as possible. 

Spring-Pump Locator. Another element which enters into 
the design of a jig and which calls for ingenuity on the designer’s 


PLntf V/£TW 




Fig. 55. Drilling Jig with V-Rest and Clanjping Device 



part, is the initial locating of a casting that is to be drilled, milled, 
or otherwise machined. Castings vary greatly, and the design of 
locator shown in Fig. 56, and termed a spring pump , is excellently 
adapted to centrally locate pieces of work that vary. In Fig. 57, 
at a, is shown the end 
view of a carbureter body 
in the rough casting, 
while b shows the holes 
drilled, using the jig in 
Fig. 58, which embodies 
the spring-pump locators 
of Fig. 56. It is obvious 

that burrs, unequal shrinkage, and other foundry causes, may 
produce such variation in castings that a positive nest, as in 
Fig. 59, is out of the question. In other words, if the nest 
were made to accommodate or fit the largest variation in the 


Fig. 56. Spring-Pump Locator 































































































38 


TOOL DESIGN 




castings, there would be such a loose fit on a smaller casting that 
it could turn in the nest and would look like Fig. 60 after the holes 
were drilled. 

Proper Relation of Operations. Here is where the designer 
must be sure that the tools are designed in such a manner that the 

sequence of operations to com¬ 
plete the piece of work is such 
that the proper operation comes 
first. For an example, assume 
that the large hole in the car¬ 
bureter body was drilled and 
bored in the first operation and 
then the holes in the four lugs 
were drilled while the carbureter 
body was positioned by the 
large hole and by the outside 
edge of one or more lugs. Then 
the castings would look as in 
Fig. 60, due to the variation in 
castings. While, on the other 
hand, if the tools are designed 
so that the first-operation jig is 
one for drilling the four holes 
in the lugs, and the body is 
located by the four lugs, then 
the second-operation jig, for 
boring the large hole, has 4 pins 
to enter the 4 holes in the lugs, 
and if the large cored hole is not 
central with the 4 holes before 
drilling, it will be so after boring 
the large hole, and the 4 holes 
in the lugs will be central with the outside lugs. 

The designer must not lose sight of this point, for his success 
depends largely upon his ability to design tools to do the proper 
operation first and in using the same holes for locating points, if 
possible, throughout the successive operations necessary to com¬ 
plete the work. 


Fig. 57. Carbureter Casting Rough and 
Finished by Use of Drill Jig 








TOOL DESIGN 


39 



‘Spring Pumps 


Fig. 58. 


iiimmtmmk 


Carbureter Body Held in Position 
by Spring Pumps 


Essentials in Design. Other points to remember in designing 
drilling jigs are the following: 

(1) Simplicity in opera¬ 
tion. 

(2) Rounded ends of 
stop or of locating points, to 
prevent chips gathering. 

(3) Absence of corners 
where chips can gather. 

(4) Small feet on the 
bottom of the jig, instead of 
a broad bearing surface, be¬ 
cause chips on the table of a 
drill press do no harm if 3 or 
4 small feet are employed. 

(5) Remember that the 
quantity of parts to be pro¬ 
duced should govern the elab¬ 
orateness of the jig. 

Devices for Rapid Opera= 
tion. Figs. 61 to 70 show 
designs of jigs that the stu¬ 
dent should become ac¬ 
quainted with thoroughly, 
as the locking devices and 
methods of holding the work, 
are applicable to boring, mill¬ 
ing, and grinding fixtures, where 
speed of operation is the prime 
factor. 

Hinged-Cover Jigs. The 
jig in Fig. 61 is of the box type 
in which the work is held by 
clamping down the cover of the 
jig; this type is not intended 
for accurate work. Fig. 62 shows 
a similar clamping method, but 
a swinging cover. 



Fig. 59. Nest for Carbureter Blank 







































































40 


TOOL DESIGN 


Screw-Bushing Jig. Fig. 63 shows the screw-bushing type. 
The bushing not only holds the work, but it also acts as a guide 
for the drill. This type of jig does not produce accurate work, 

as the free fit of threads 
on the screw bushing 
permits it to tilt slightly, 
changing the center loca¬ 
tion of the hole in the 
work. 

Multi - Spindle Jig. 
Fig. 64 shows a simple 
type of jig designed for 
a multi-spindle drill 
press. Clamping devices are not as essential on jigs when a 
multi-spindle press is used, due to the fact that all drills are 
cutting at the same time, which prevents the work from shifting. 

Drilling-and-Reaming Jig. Fig. 65 can be elaborated upon, 
but the essential point is in being able to drill and ream in the same 
jig without removing the drill bushing. In operation the work is 
drilled by the bushings, then the jig is reversed and a reamer or a 
counterbore further machines the work. A bushing is used for 
the counterbore, but for a reamer a clearance hole or a soft bushing 



Fig. 61. Hinged-Cover Box-Drill Jig 



Fig. 62. Box-Drill Jig with Swinging Cover 


should be used, as a reamer is rendered useless after it has been 
reduced 0.001 inch in diameter and wears away quickly while 
revolving in a hardened bushing. 





























































































TOOL DESIGN 


41 



Indexing Type. Fig. 66 shows an indexing type of jig. The 
object in using the indexing plate is, that when a number of holes 
are to be drilled in a circle it 
is a more accurate method 
than if the jig were made as 
in Fig. 67. Assuming that 
the work to be drilled is the 
plate in Fig. 68, only 1 inch 
in diameter, then, by making 
the index plate in Fig. 66, 
say, 6 inches diameter, and 
by very accurately locating 
the index notches in its edge, 
we could allow slight dis¬ 
crepancies in the notches, 
for when the variations are 
reduced to 1:6 they are negli¬ 
gible. A better understand¬ 
ing of this point can be had 
by noting the difference in 
travel of the rim of a wagon 
wheel and the hub. 

Slip Bushing. The stu¬ 
dent must bear in mind that the designing of jigs must not be con¬ 
fined to the crude designs shown herewith, but he must become 
familiar with the prin¬ 
ciples involved, such as 
locking devices, methods 
of locating, etc., a n d 
when designing a jig it 
is often best to embody 
several principles in a 
single jig in order to 
obtain the greatest effi¬ 
ciency. This idea is 
illustrated by slip bushings which are often used advantageously 
where a reaming, counterboring, or tapping operation is desirable 
without removing the work from the jig. Fig. 69 shows a plate 



Fig. 63. Drill Jig with Screw Bushing 



Ka<3$ 
ip Space 


Fig. 64. Box Jig Designed for Multi-Spindle 
Drill Press 




























































































































42 


TOOL DESIGN 


which embodies the slip-bushing design, the lower view showing 
the bushing withdrawn. 



Master-Plate Type. Fig. 70 shows the most accurate design 
of jig. It is noted that the jig is attached to the faceplate of a 



bench lathe and that the jig containing the work is indexed, employ¬ 
ing a master plate that has been accurately made and adopted as 
the shop master. The design shown in Fig. 70 is in its simplest 




















































































































































































TOOL DESIGN 


43 


form, and the designer must exercise his ingenuity in adapting the 
principle involved to the design of the jig desired. As each hole 



Fig. 67. Simple Method of Holding Circular Piece for Simultaneous Drilling 


is spotted and drilled, the hole is made 
perfectly round and directly opposite 
the hole in the master plate by boring. 

Boring and Milling Jigs. Boring, 
milling, and other jigs are designed 





Fig. 69. Slip Bushing 

// 

practically the same as drilling jigs, except that they are usually 
attached to a machine and the holding device, usually a screw 
clamp, is made more rigid while the machining is being done. 























































































































































44 


TOOL DESIGN 





Bi-nr-rK 
Whtch Plsite 
( Work r) 



Fig. 70. Master-Plate Jig for Very Accurate Drilling 


GAGES 


Classification and Usage. Gages are classed as ring, plug, 
snap, depth, male and female profile, receiving, and thread gages. 

Limit Gage. The close limits to which many products are 
made to insure absolute interchangeability make it necessary to 
employ gages for almost every operation, and in many instances 
limit gages are required. Assume that the piece in Fig. 71 is to be 



Fig. 71. Example of Piece to be 
Made of Accurate Diameter 



Fig. 72. Ring Gage of 
Given Diameter 


made, which calls for dimensions in tenths of thousandths. It is 
an unwritten rule almost universally used by designers to specify 
by the dimensions the accuracy required. For instance, a dimen¬ 
sion given in fractions is understood by most tool-makers to mean 
that scale measurement is accurate enough. When the dimension 



















































































































TOOL DESIGN 


45 


is in thousandths of an inch the accuracy must not vary more than 
one-thousandth, and when a dimension is specified in tenths of thou¬ 
sandths the variation must not exceed a ten-thousandth of an inch. 

If a ring gage, Fig. 72, or a 
snap gage, Fig. 73, made exactly 
0.6875 inch in diameter, were given 
the average operator employed in 
machining the piece in Fig. 71, 
the accuracy or variation in the 
0.6875-inch diameter would be a 
matter of personal equation. That 
is, the gage would not be fool¬ 
proof, for as long as the work 
enters the gage the operator would 
continue to make the pieces, 
whereas the diameter might be 
several ten-thousandths under size. 

To eliminate this personal equation the gage is designed as in Fig. 74; 
one gage is made 0.6875 inch, while the other gage is made 0.6874 
inch, and in operation, if the work enters the 0.6875-inch gage 




Fig. 73. Snap Gage of Given Diameter 


Fig. 74. Limit Gage for Gaging Fig. 71 

and not the 0.6874-inch, then the work must be of a diameter some¬ 
where between the two. This type of gage is called a limit gage. 

Snap Gage . Various designs of limit snap gages are shown 
in Figs. 75, 76, and 77. The gage in Fig. 77, while more expensive 







































46 


TOOL DESIGN 


than the other types of snap gages, is the most suitable design 
when subjected to constant use. Gages wear quickly, losing their 




Fig. 77. Snap Gage Designed to Correct Wear 



Fig. 78. Circular Plug Gage 



Fig. 79. Rectangular Plug Gage 


trueness, and all that is nec¬ 
essary in connection with 
this latter style is to lap the 
plates a, b, and c, perfectly 
flat and to reassemble the 
gage. The plates d and e 
are made of proper thick¬ 
ness, and they accurately 
space the plates a, b, and c. 

Plug Gage. Figs. 78 
and 79 show the designs 
of plug gages most gen¬ 
erally used. Figs. 80,81, 
and 82 show the limit 
type of plug gage. 

Receiving Gage. Figs. 
83 and 84 show two de¬ 
signs of receiving gages. 
These gages should be 
designed for use only 
when the nature of the 
work demands extreme 
accuracy. 
























































TOOL DESIGN 


47 



Fig. 80. Plug Gage with Limits Opposed 



Fig. 81. Plug Gage with Limits in Series 



Fig. 82. Square Form of Limit Plug Gage 



— 

Fig. 83. Receiving Gage 



Fig. 84. Hand Form of Receiving Gage 






















































































48 


TOOL DESIGN 




Fig. 85. Simple Forms of Profile Gage 



Fig. S6. Simple Depth Gage 




Fig. 87. Depth Gage Depending for Its 
Accuracy on Operator 


Fig. 88. Accurate Depth Gage of 
Lever Form 



























































































TOOL DESIGN 


49 



Profile Gage. When the work is of a nature that it requires 
a profile gage to maintain the contour or outside shape, the designer 
should start with a master profile gage to which the profile gages 
may be fitted for use when making the formed milling cutters, fly 
cutters, or forming tool, and 
the working profile gages a, 

Fig. 85. In the illustration 
the male and female profile 
gage is in its simplest form. 

Depth Gage. Figs. 80, 

87, 88, and 89 show depth 
gages. The gages in Figs. 88 
and 89 are designed for very 
accurate work, while the 
accuracy of those in Figs. 86 
and 87 is governed by the 
operator. 

Bench Micrometer. The 

gage shown in Fig. 89 is 
called a bench micrometer, 
and there are several good 
makes on the market. This 
gage can be used in place of 
snap, ring, and depth gages. 

When used as a thickness 
gage, the work is laid on the 
table which is adjustable up 
or down, and in operation the gaging point actuated by the 
hand lever is brought to bear on the work, and the thickness of 
the work is indicated by the pointer on the dial in thousandths 


Fig. 89. Dial Depth Gage 

Courtesy of American Watch Tool Company, 
Waltham, Massachusetts 


of an inch. 


SUCCESSFUL DESIGNING 

Problem of Sequence of Operations. The economical manu¬ 
facture of a product does not depend solely upon the proper design 
of tools; the sequence of operations through which the product 
passes also plays a very important part. Therefore the designer 
may tool up for a certain product, and the tools may be of the best 













50 


TOOL DESIGN 


design imaginable—embodying quick loading and unloading features 
and clever locking devices, all of which tend to make the rapid 
handling and completion of the parts all that may be desired— 



Fig. 90. Carbureter Body Shown in Section 


but the actual economical feature can be lost through not doing 
the proper operation first, and it too often happens that a third 
tool is made necessary to correct discrepancies that are caused by 

the improper sequence of 
operations. 

The carbureter body, 
Fig. 90—with its thin deli¬ 
cate walls, the two bores 
which must be absolutely 
in line, and an outside 
of rough casting scale— 
is an excellent product to 
demonstrate the necessity 
of carefully laying out 
the proper operations be¬ 
fore designing the tools. 

Fig. 91. Carbureter Body Clamped to Faceplate rru 

lhe difference in diam¬ 
eters between the inside bore of the body and the outside diameter 
of the valve a is limited to not more than 0.002 inch. 

The following line of reasoning must be followed to be a suc¬ 
cessful designer: 


























































































TOOL DESIGN 


51 


Manner of Holding Work. Distortion by Chuck Jaws. The 
first thought naturally would be to grip the body in a chuck having 
special jaws to hold it, but the fact that the outside of the body 


Chuckincj Piece 



■- > - 
i 

a 

i 

i 

i 

_ h - 



Fig. 92. Holding Small End of Carbureter Body by Means of Chucking Piece 


is a rough casting and the walls are thin precludes the use of chuck 
jaws, for the reason that one small high spot on the casting would 
cause the pressure of the jaws to center on this high spot, resulting 



Fig. 93. Carbureter Body with Special Lugs for Holding 

• // 

in distortion of the body; then, if the body were finished while under 
distortion, the finished hole would be out of round when the pressure 
is released. This fact makes it necessary for the designer to depart 





















52 


TOOL DESIGN 


from the usual design of tools and to devise special tools, depending 
almost entirely upon his inventive ability, and upon a fund of 
experience and knowledge of every conceivable mechanical device 
From his knowledge he must mentally select a certain principle 

involved possibly in 
some one jig, and an¬ 
other principle or move¬ 
ment embodied in some 
other fixture, and so on, 
until by putting these to¬ 
gether he can complete 
a satisfactory tool to 
meet the requirements 
of the operation at hand. 
Therefore a method 
other than chuck 
jaws must be devised 

Fig. 94. Carbureter Body Held by Faceplate with for holdin 0, the body 

Special Lugs ® J 

for the first operation. 

The thought occurs that the wide base b, Fig. 90, is an excellent 
surface to clamp against a lathe faceplate containing special holding 




i -!=> 

- V 


A 



Fig. 95. Lathe Set Up for Roughing Cutter 

fixtures as in Fig. 91. However, the designer immediately discards 
this method, for it is noted that the larger bore cannot be machined 
in this position, and, as the two bores must be in absolute alignment, 




































































TOOL DESIGN 


53 


it would mean that the work would have to be machined first on 
one end and then on the other, which is decidedly wrong, for eccen¬ 
tricity will creep in. Following the rule of machining as many sur¬ 
faces as possible at one setting, a device must be employed that 
holds the work by the 
small end, so that both 
diameters can be finished 
at the same setting and C 

while the body is not \ 

— - 

under distortion. By so f|| 
doing, absolute alignment 
is possible. 

Use of Chucking 

Piece. The problem now Fig. 96. Inside Hole of Carbureter Body Recessed before 
1 1 . „ Using Roughing Cutter 

at hand is to satisfac¬ 
torily hold the body by the small end. A chucking piece a , 
Fig. 92, could be cast on the body simply to provide a holding mem¬ 
ber, then after the body is machined the chucking piece could 
be cut off. This chucking piece could distort the body in two ways: 

(1) by the pressure of the chuck jaws on the chucking piece; 

(2) since in all castings there are internal strains and, to a great ex¬ 
tent, the scale prevents these internal strains exerting themselves, the 
process of roughing out 
the bores to remove the 
strains, then final-finish¬ 
ing the bores, and lastly, 
severing the ring or 
chucking piece would 
further release the strains, 
and the finished bore on 
the small end of the body 
would not be round. 

Special Lugs. 

Knowledge of these facts 
leads the designer to add a special lug a, Fig. 93, on each side of 
the body, and the body is finished complete at one setting, as in 
Fig. 94, the lugs then being cut off, or, if possible, left on the body. 
The design of the body or product at hand can often be cleverly 



Fig. 97. Use of Guide Bushing in Boring Central Hole 
































































54 


TOOL DESIGN 


arranged so that the members added as a holding means look like 
part of the intended design. 

Method of Machining. Having decided to hold the body, as 
in Fig. 94, one must go still further, for the methods that might 
be employed in machining the two bores could produce inaccurate 
alignment. When casting the body, cores are placed in the mold 



Fig. 98. Typical Tool Data Sheet 

to produce the bores. This leaves a scale inside the bores, and, as 
the cores invariably shift, the resultant bores either are not in 
line, or, if in line, are not concentric with the outside of the body. 
In either case the bore is eccentric if the outside of the body runs 
true when attached to the faceplate. 

Boring. If a roughing cutter, Fig. 95, is used to machine the 
large bore nearly to size, and if the large bore is not running true, 














































































































TOOL DESIGN 


55 


the cutter follows the hole, and, after a finish reamer machines 
the large bore, the diameter may be correct but the bore is still 
running eccentric. Therefore, to insure the roughing cutter starting 
centrally, the outer end of each bore is recessed to cutter size for a 
short distance, as in Fig. 96, using a single-pointed boring tool. 
The roughing cutters mounted in the turret head of a monitor 
lathe can then be used to rough out the bores, due allowance being 
made to leave enough stock for the finish tool to clean up the hole. 
For absolute alignment of bores a single-pointed tool should be used 
to finish-size both bores, for a reamer cannot be depended upon 
to keep the hole concentric, although it produces the desired 
diameter. 

Use of Guide Bushing. Another method of machining the bores 
would be to rough out both bores to remove the scale, then finish 
the large bore and insert in it a concentric hardened-steel bushing, 
Fig. 97, the central hole in which is used to guide the cutter for 
finishing the small bore. The student, however, can readily see 
wherein there are chances for inaccuracies to creep in when the 
bushing is employed. “How many chances for errors?” would make 
an excellent examination question. The answer is three, as follows: 

(1) difference between diameter of bushing and bore in body; 

(2) difference in diameters of hole in bushing and of reamer; and 

(3) eccentricity of hole in bushing. 

Conditions for Accuracy. The points that must be considered 
by the designer to produce the carbureter body, or similar 
work where holes must be in absolute alignment or concentric 
with outside, and where holes must be perfectly round, are as 
follows: 

(1) Use a holding device that does not distort. 

(2) Lay out the sequence of operations so that the work can 
be completed in the least number of operations. 

(3) Do all machining that is feasible at one setting, to insure 
concentricity. 

(4) Do not trust a reamer to final-size holes that must be 
in line with each other. 

(5) Do not machine one end then reverse the work and machine 
the other end, if possible to avoid, for any error caused in either 
end is doubled when the work is reversed. 


5G 


TOOL DESIGN 


(6) When finish-sizing holes or circular outsides that must 
be in absolute alignment, use a single-pointed tool, not guided. 

(7) It makes no difference whether the work revolves and the 
single-pointed tool is stationary, or whether the single-pointed tool 
revolves in work that is stationary. 

The valve a, Fig. 90, of necessity must be made just as accurately 
as are the bores in the body, and the same ideas must be followed 
out as were outlined in connection with the body, i.e., do all turning 
possible at one setting, using a single-pointed tool to guard against 
eccentricity, etc. 

Outlining Methods. To complete the outline of tool design— 
supplementing the question of why a certain design is adopted— 
and to enumerate the detailed methods that'must be followed by 
the designer, assume that you have been given a blue print, Fig. 98, 
which gives the detailed dimensions of the three pieces shown in 
Fig. 90, and that you are instructed to proceed with the tooling 
up for a large production job. 

Order of Operations. The first step is to procure a long strip 
of paper and rule it, or to have a quantity printed, as in Fig. 99, 
for a data sheet. The next move is to select piece No. 1 and lay 
out the sequence of operations by mentally going over each opera¬ 
tion necessary to complete the piece satisfactorily. The order of 
operations as finally decided upon is enumerated on a pad in numerical 
order, Fig, 100. 

Tools Required. After all pieces have been thoroughly gone 
over many times and the final operations written out, the next step 
is to outline the tools required. On the data sheet are written the 
operations and all the tools required, even to standard drills, 
reamers, etc., as in Fig. 99. The tools are then assigned a number 
for record purposes. 

Correlation of Units. Before designing each tool, a careful 
classification should be made so that the tools designed first shall 
produce a secondary unit. For example, a product is made up of 
pieces parts, which in turn go to make up a secondary unit, and the 
secondary units finally make up the primary unit, which is the 
completed product. A graphical illustration is partially shown 
in Fig. 101. The object in designing the tools so that a secondarv 
unit may be completed is that, as fast as the tools are made, trial 


TOOL DESIGN 


57 


models should be made from the tools and the trial models, if they 

' V 

are piece parts of a secondary unit, can be assembled one to the 
other, making an assembly of a secondary unit which is a check 
on the tools. If a tool were made to produce the float in a carbu¬ 
reter, and the next tool made produced the air valve, these tools 
could not safely be allowed to run off a quantity of pieces until all 
tools were completed and a trial model assembled from pieces made 
from the tools. In the arrangement in Fig. 101 the 1-inch carbu¬ 
reter is of course the primary unit; the throttle-body assembly and 
the float assembly are both secondary units that go to make up 


JDw<j.tfQ C-£92 Tool Dn th. Sheet 

Piece ri° 1 


Operth 

If* 

Description 

Tools Required 

Tool R°- 

Dwq. 

Campulm 

Machine 

D**g. given 
Tool Room 

Old 

tie rv 


jfcTumj tAnmJi 

} 3oar, if traps 

104 



rf jOcCot* aZuCL 




.24-8-24 DPoo. 




II 




sPmar) TlarjSs .575 


4-03 

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illnrmJh. tAn tndqn. (RcruqJr > 

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404 

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P/udPJU* Tfanis 


405 

,z /z//s 

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/Z A/,S 



7 / 







Dru&P; & MaA c Jijy-Pi, fisYxd, 

vfrsttAir (lPloucA, 

95 






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srf Ttrrrf^ 


407 

'VsPs 

•t II 

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5Ljck 


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ifo^smJ/nq f/mf. Jo\ JJaAL. 


408 

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409 

l2 /4/,S 

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/z A/,s- 



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'V6/,ST 




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r P 

Of TpA jor/. anrp 


404 

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4 09 

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/ 7 A/s- 


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Fig. 99. Order of Performing Operations 


the primary unit, while the pieces that make up the secondary 
units are piece parts. If the designer will systematically lay out the 
tools and parts as outlined, the danger of missing some tool or 
piece may be reduced to the minimum. 

Design of Product. Another point that governs the design 
of tools, and in a sense comes within the tool designer’s domain 
to a great extent, is the design of the product. In up-to-date 
engineering departments the product designer consults the chief 
tool designer before turning over to the tool designer the finished 
product for tooling up. For instance, a model device may have 











































58 


TOOL DESIGN 


been perfected of sheet metal, but certain parts of this device are 
held together by screws, which means tapping operations and the 
cost of screws besides the slow operation of putting in the screws. 



Fig. 100. The Units and Their Classification in Any “Tooling-Up” Process 


The tool designer, due to his training, notes that these certain parts 
could be held together satisfactorily by punching and bending down 
an ear, which in turn fits in a slot and is then riveted over, or bent 
over, eliminating the tapping and the cost and handling of screws. 



Fig. 101. Diagrammatic Layout of Carbureter Operations into Units 


Collaboration. The successful designer does not depend 
entirely upon his own ideas, but obtains the views of all interested. 
There is a shop phrase that “there are forty-nine ways of doing 























TOOL DESIGN 


59 


every job”, and a designer who places himself upon a pinnacle and 
refuses to confer with designers and tool-makers under him or with 
the foreman who is to use the tool always wonders why he does not 
advance, and this type of designer will be found too frequently 
looking for a new position. Oftentimes the foreman who is to use 
the tool may recall some particular job that is identical with the 
one at hand, and can greatly aid the designer. Therefore, the 
designer must not allow personal pride or conceit to govern his work, 
but should make it a practice to get every idea and to listen to every 
suggestion possible. While a suggestion may not be applicable 
to the job at hand, it should be mentally retained and sooner or later 
may be employed. 

Observation. Observation plays an important part in making 
a successful designer. For instance, should the designer see in 
operation some complicated machine or fixture, he should at least 
make it a point to note mentally one or more movements, even if 
the entire principle of the machine cannot be grasped at a casual 
glance. The reading of journals devoted to the mechanical field 
is one of the greatest aids to success; every article contains some 
unique kink or valuable point, and a reader may grasp in a few 
minutes’ reading what has required years of travel and experience 
for the author to gather. 





TYPICAL AUTOMOBILE STAMPINGS 

Courtesy of Toledo Machine and Tool Company, Toledo, Ohio 


• sa 




















PART II 


DIES AND SHEET METAL 

STAMPING 


DIE-MAKING AND USAGE 

Study of Details. Having become familiar with the various 
types of dies for stamping sheet metal, together with a general idea 
as to the methods employed in making the dies as outlined in a gen¬ 
eral way in Tool-Making, Part III, it is now essential that the student 
thoroughly understands the manner in which a die-maker sets about 
to satisfactorily complete any die. This article deals with die-making 
proper, entering into each minute detail and description of the 
various methods and shop kinks practiced by the expert die-maker, 
together with a description of why a certain piece is made first, and 
why it is made a certain way; taking up the next piece, and from 
this to a third, and so on step by step, until the completion 
of the die. 

Grasp of Job Essential. The first step practiced by an expert 
tool-maker when about to make any tool is to thoroughly understand 
the drawing from which he is to work; and from a thorough study of 
the drawing the completed tool in operation can be mentally pic¬ 
tured. The complete understanding of the job at hand is absolutely 
essential before a cut is made on any piece of steel, for the very 
nature of the work governs largely which piece should be made first. 
It is better to spend a whole day, if necessary, in studying the draw¬ 
ing of a complicated tool than it is to have only a vague idea as to 
the working principle, for more often it will be found that, due to 
lack of thoroughly understanding the mechanism, several days’ time 
is lost on a spoiled piece of work. 

It is the importance of understanding the working of the 
machine that emphasizes the necessity of every tool-designer and 
die-maker being an expert mechanic. 



9 


DIES AND METAL STAMPING 


BLANKING AND SHEARING TYPES 


MAKING SIMPLE PUNCH AND DIE 

Size Factor. In Fig. 306 of Tool-Making, Part III, are shown a 
blanking punch and die for use on heavy stock such as boiler plates. 
In a simple tool of this character it is immaterial which part is made 
first. But, should this same type of tool be required for piercing a 
small hole in heavy stock, the tendency would be to spring the 
slender punch, and, therefore, in such a case, the punch should be 
supported and guided by the stripper. Assuming that the punch is 
of J-inch diameter and is to pierce hard rolled stock J inch thick, 
the first step is to find the difference in diameters between the punch 
and the die. 

Clearance. The rule for clearance is to multiply the thickness of 
stock in thousandths of an inch by .06; the answer being the differ- 

__ ence in thousandths of an 

KirmTnf^^l 

inch between the punch and 
the die. 

Whether to increase 
the size of the die or to 
decrease the size of the 
punch depends upon the 
nature of the stock and 
whether the piece punched 

Fig. 1. Section of Die in Which Soft Stock Is Used . , r p , • 

out must be or a certain 
diameter or whether the diameter of the hole must be maintained. 
If the blank or piece punched out must be of a certain diameter, 
say .250 inch, then the die is made .250 inch, whereas, if the hole 
pierced is to be maintained .250 inch, then the punch is made .250 
inch in diameter, and the clearance or difference between the punch 
and the die is obtained by increasing the size of the die. This is 
only essential, however, where the diameter of the hole or of the 
blank is to be maintained in thousandths of an inch. 

Resistance of Sheets. When punching holes in sheet metal, the 
actual diameter of the blank, using the same die and punch, varies 
with the temper of the stock. For instance, on hard rolled stock 
the blank would break somewhere between the diameter of the 
punch and that of the die as exaggerated in Fig. 1. This is more 



Vie 




































DIES AND METAL STAMPING 


3 


noticeable on heavy stock as the thick stock is stiff enough to with¬ 
stand the pressure of the punch. If soft stock were used in a die 
as in Fig. 1, the stock would bend down between the punch and the 
die, causing a heavy burr on both the blank and the hole. A tight- 
fitting punch and die also causes heavy burrs on both hole and blank, 
when punching thick stock 

Binding. The main reason why a difference in the diameters 
of punch and die for piercing thick stock is necessary is to prevent 
breaking the punch. If a punch that snugly fits the die were used to 
pierce J-inch stock, the stock would be such a tight fit on the punch 
that it would be hard to strip the stock from the punch. Again, 
the severe rubbing of the punch as it passes through the stock would 
cause the punch to roughen, or, to use the shop term, to pick up, 
which causes the stock to stick to the punch, and which is one cause 
of the punch breaking. 

Another cause of breaking, and one which the die-maker must 
guard against, is when the underside of the stripper, where the stock 
comes in contact with it in stripping, is not parallel with the die, or 
rather is not at right angles with the travel of the punch. It is 
readily seen that, if J-inch stock is snugly gripping a small punch 
and the stock comes in contact with the underside of a stripper 
plate which is on an angle, the stock is going to adjust itself to the 
surface of the stripper, which will snap off the end of the punch. 

Guiding. Following the rule for clearance given above, we find 
the difference between the punch and the die to be .0075 inch, and, 
assuming that the punch is of small diameter, it now becomes impor¬ 
tant 'which part is made first, as the punch should be guided and 
supported. The term guided, when applied to a punch attached to 
the ram of a power press that travels in a positive channel, appears 
at first glance to be a misnomer, but any uneveness of the stock 
surface, such as caused by a slight kink in the stock or even by a 
piece of foreign substance on the stock, causes the punch to be 
deflected from its line of travel, resulting in a broken punch. 

Sequence of Operations. Mdicing Die Bushing. The sequence 
of operations for one good method of making the punch and die, 
Fig. 2, is to cut off a piece of round tool steel for the bushing a, 
Fig. 2, say 2 inches longer than desired, and, gripping the steel in 

a lathe chuck, to rough-drill the hole to within, say, ^ inch of size, 

A 

* 


4 


DIES AND METAL STAMPING 


then to turn the outside diameter to the desired dimension, and 
finally to bore the hole to the desired size. Boring and turning at 
the same setting insures concentricity of the hole and the outside, 
providing, however, that one diameter is not finished before start¬ 
ing to machine the other diameter. For instance, if the outside 
were turned to exactly the right diameter, then the hole spotted, 
drilled, and bored, the pressure of spotting and drilling might 
cause the rod to spring or to shift in the chuck, resulting in the 
finished hole being eccentric with the outside. The tool-maker 
must constantly guard against any element of chance. 

After both diameters are obtained, the bushing is cut from the 
rod, using a cutting-off tool in the tool post of the lathe. The clear¬ 



ance in the bushing can be bored by setting the slide rest at the 
desired angle, say \ of a degree—the shop term for expressing 0° 30'. 
If a taper reamer is employed, we have no assurance that the finished 
taper hole will be concentric with the outside, as the reamer can be 
started on an angle with the hole. The bushing is now hardened 
and drawn to a dark straw color. 

Making Die Shoe. The next step is to plane the bottom of the 
die shoe. As the top and bottom surfaces of die shoes must be 
parallel, it is obvious that we must hold the die shoe by clamping it 
to the bed of a shaper or on the faceplate of a lathe. If gripped bv 
its rough sides in a shaper vise, difficulty would be experienced in 
obtaining parallel surfaces. 














































DIES AND METAL STAMPING 


o 


Alignment of Stripper. After machining the top surface of the 
shoe, the bushing is inserted. At this point is where the die-maker 
must be careful on this particular job. The haphazard trust-to- 
chance method is to drill and counterbore the hole for bushing, drive 
in the bushing, attach the stripper by means of screws, then put the 
hole in the stripper by transferring through the hole in the bushing. 

The more accurate and workmanlike method is to make the 
punch after machining the top surface of the shoe, then to make and 
attach the stripper to the die shoe by screws and well fitting dowel 
pins. Lay out and prickpunch on the stripper face approximately 
the desired location for the die hole, and strap the die shoe to the 
faceplate of the lathe. It should be remembered that whenever any 
work is clamped to the faceplate of any machine, the faceplate with 
the work attached is always to be revolved one complete revolution 
by hand to make sure that projecting corners of the work clear all 
parts of the machine; this will prevent many accidents. 

Indicate the prickpunch mark to be comparatively true. The 
shop phrase indicate means to place the contact point of a test 
indicator, as shown in Fig. 3, against the work, and, when the work 
is properly located, the indicating pointer will not deviate from a 
graduation on the arc. Graduations on test indicators are usually 
so spaced that their intervals represent one one-thousandth of an 
inch each. If the indicating pointer moves two graduations during 
one complete turn of revolving work, it means that 'the work is 
actually out of true only one one-thousandth. 

Spot the stripper and drill the hole clear through both the 
stripper and the die shoe. Then bore the hole in the stripper to fit 
that portion of the punch that enters the stripper. The stripper is 
now removed, but the die shoe is not disturbed, and the hole for the 
bushing is bored in the die shoe to a driving fit. The reasons for 
boring the stripper are many. First, we can make the hole fit the 
punch, which would not be so easy if the hole in the stripper were 
drilled—the drill being guided by the hole in the die which would be 
somewhat larger than the drill. It is obvious that the hole in the 
stripper might not be directly in line with the hole in the bushing. 
Again, by drilling through the die shoe the shoe would rest 
either on the screw heads on the stripper, or on the face of the 
stripper, or on the parallels, any one of which may cause the drill 


6 


DIES AND METAL STAMPING 


to pass through the stripper on an angle. Granting that the paral¬ 
lels, or whatever is used, will insure the bottom of the die shoe 


Fig. 3. Various Positions of Test Indicator in Shop Work 
Courtesy of L. S. Starrett Company , Athol, Massachusetts 



resting parallel with the table of the drill press, it does not follow 
that the table of a much abused drill press is at right angles with the 
travel of the drill-press spindle, and the hole that is drilled and 























































































































































DIES AND METAL STAMPING 


7 


reamed through the stripper may be at an angle, so that when the 
die is set up for work in the press the punch will have to spring 
every time it passes through the stripper, which will eventually 
cause breakage of the punch. 

It is attention to these apparently unimportant details that 
distinguishes the master workman from the ne’r-do-well class. At 
first glance, the punch and die shown in Fig. 306, Tool-Making, 
Part III, looks insignificant—all that is necessary apparently being 
simply to turn up a round piece, bore out a round hole, attach a 
strip across the top, and the die is complete—and on some classes 
of work this is true, but that same simple die may be called upon 
to perform work that requires greater care in die-making than the 
haphazard method. 

Irregular Shapes 

Question of Steel. Sheet Stock. Fig. 307, Tool-Making, Part 
III, shows that type of die known as an irregularly shaped blank¬ 
ing die. When making this die the die-maker should follow the blue 
print absolutely, unless, of course, he discovers an apparent mistake, 
in which case the foreman’s attention should be called to the fact. 
If a blue print is furnished, the dimensions and the horizontal angle 
at which the die is to be laid out appear on the print, but if no draw¬ 
ing is furnished, the die-maker should first of all ascertain what 
width and what thickness of stock is ordered for the job, as the 
width of the stock governs the angle at which the die must be laid 
out on the die block. 

The angle of the die in relation to the die block is very impor¬ 
tant, if the blank is to have subsequent bending operations, due to 
the fact that in rolling the sheet stock there is an actual grain, and 
bending the blank with or across the grain is almost analogous to 
bending wood. A piece of sheet stock can be bent at right angles 
having a sharp corner, if the bend comes crosswise of the grain, but 
if the bend is made lengthwise of the strip, the stock will break. 
Therefore, a die-maker, knowing this, should not proceed with a die 
unless he has full information. This is another instance of elimi¬ 
nating every element of chance or, that other bugaboo, of taking 
things for granted. 

Die Stock. Assuming that the blank is to remain flat and that 
the sheet stock is ordered just wide enough to punch one blank from 


8 


DIES AND METAL STAMPING 


the strip, the first move is to select the die steel, for it is absolutely 
essential when hardening the die to know what brand of steel the die 
is made from. Some makes of tool steel are more expensive than 
others, and certain makes are made to harden in oil which prevents 
distortion to a great extent, while if the oil hardening steel were hard¬ 
ened in water, the die would crack. On plain dies, such as Fig. 4, 
any good grade of carbon steel which is lower in cost will answer, as 
there are no delicate points on the die to distort or to present 
chances of cracking. If there is no distinguishing mark on the 
steel, it is best to cut a small piece from the bar, drill several holes 
in it, and use it as a test spiece, hardening it in water. 

Preparing Die Block. Having ascertained the brand of steel, 
the block is cut from the bar, and the first surface to be planed or 
milled should be the widest surface; this giving a broad bearing for 
the machined surface to rest against the solid jaw of the vise. The 
edge is next machined, then keeping the broad machined surface 
against the solid jaw, the block is turned so that the edge just 
machined rests on the bottom of the vise. We now have two 
machined surfaces resting on two machined surfaces of the vise, 
and the other edge is machined. A pair of parallels are placed on 
the bottom of the vise, and the broad finished surface is placed on 
the parallels, which causes the two machined edges to come in con¬ 
tact with the vise jaws. We now have three machined surfaces to 
position the block when machining the other broad surface. At 
least one end of the die block should be machined at right angles, or 
to use the shop term, machined square with the edges. The object 
in machining the end is to aid later in laying out. 

Working Face. Whichever side is to be used for the top or 
working face of the die should have at least ^ inch of stock removed, 
due to the fact that in hot rolling tool steel the outer surface becomes 
oxidized and is decarbonized to a certain extent, and, unless enough 
stock is removed to get under this burned surface, the die may cause 
trouble in hardening as the top surface may be soft in spots, in 
connection with which, if the die is rehardened in an attempt to 
obtain an entire hard surface, the repeated hardenings invariably 
produce cracks in the die. If a die, after the first hardening, should 
appear soft in spots, it would be better to draw the temper and to 
grind, say, ^ inch from the top surface in order to remove all burned 


DIES AND METAL STAMPING 


9 


metal. If the decarbonized surface caused the soft spots, the entire 
surface of the die would be hard after grinding, and rehardening 
would be unnecessary. Also, prior to laying out the die, the top 
surface of the die block should be machined very smooth and should 




Fig. 4. Drawing of Piece to Be Prepared 


be further smoothed with emery cloth. Instead of laying the grain 
one way when using emery cloth, it is better to polish with a circular 
motion, as lines scribed on the die are more pronounced over circu¬ 
lar emery marks than over straight ones. When nicely smoothed 



Fig. 5. Scribing Center Lines on Block 


the surface should not be touched, especially with the fingers, as 
grease marks interfere with the proper bluing of the surface. 

The block is now placed, polished side up, over a forge and heated 
slowly until a deep blue appears on the surface, at which point the 
color is set by quenching, preferably in oil. A scribed line is more 
































































































































































10 


DIES AND METAL STAMPING 


pronounced on a blue surface than if a copper-sulphate blue-vitriol 
solution is used, and another objection to the coppered surface is 
that it peels off when drilling and filing the die, which removes the 
scribed lines. The die block is now ready to lay out. 

Laying Out Die. If a templet or model blank is furnished from 
which to make the die, then the clamp shown in Fig. 332, Tool- 
Making, Part III, is used to securely hold the tepplet on the face 
of the die block while the outline is traced with a fine sharp pointed . 
scriber. If, however, a drawing, Fig. 4, of the piece is furnished, 
the first step is to scribe center lines on the block as in Fig. 5, in 



Fig. 6. Method of Scribing Center Lines 


order to transfer the outline, as shown on the drawing, to the face 
of the die. 

Referring to the drawing, Fig. 4, we note that the overall length 
is 2 inches and the width is 1 inch. A fine prickpunch mark is 
placed at the intersection of the lines, the divider points are set 
1 inch apart, and a section of a circle is scribed at each end as at a, 
Fig. 6, and, by again referring to the drawing, it is noted that the 
inside dimension is 1J inches. The dividers are set at one-half this 
—| inch—and the lines bb are scribed. The width being 1 inch, 
the dividers are set at | inch and the lines cc are scribed. The lines 
del, ee, and jj are now scribed, using the surface gage or scratch 
block as at B, Fig. 6. This is why one end of the die block was 

































DIES AND METAL STAMPING 


11 


machined at right angles to the edges when machining. A square 
can be used instead of the surface gage, but it is not quite as handy. 
The angle lines are 
scribed by setting the 
protractor at 45 degrees 
and scribing along the 
blade, as at Fig. 7. 

Shaping of Die. 

Roughing Out. If a die 
filing machine, Fig. 319, 

Tool-Making, Part III, 
is at hand, a narrow 

hack-saw blade is placed Fig. 7. Scribing Lines by Means of Protractor 



through the hole drilled in the corner of the die, and the blade 
with teeth pointing downward is secured in place of the file, as 



































































12 


DIES AND METAL STAMPING 


in Fig. 8. By tilting the table the desired angle the piece in 
the center of the die can be sawed out very close to the line, with 
the desired clearance, which leaves very little to file. If a die filing 
machine is not used, the center piece is removed by drilling a 
series of small holes just inside the line and by cutting out the 



web between the holes with a broach, as described in connection 
with Fig. 312, Tool-Making, Part III. After the broach has been 
driven nearly half way through from both sides of the die, the center 
piece can be forced out. The die then looks as in a, Fig. 9. 

The webs between the drilled holes can be removed easier and 
quicker by means of a cold chisel and hammer than by filing, but 
















































































DIES AND METAL STAMPING 


13 


great care must be exercised when using a chisel, for there is danger 
of cutting too deeply. After the greater part of the webs are 
removed, the die is gripped in the vise in a horizontal position, top 
side up, and with a coarse file the remaining webs are removed by 
filing up and down as indicated in b, Fig. 9. Filing in this position 
has several advantages, but for final-filing to line and to straighten 
the filed surface better results are obtained by filing crosswise as 
in c, Fig. 9. 

The most expert die-makers cannot file a die in one direction 
without producing a slightly rounded surface as exaggerated in d, 
Fig. 9. As the line is approached in filing, the filed surface should 
be draw-filed frequently. By filing crosswise, then draw-filing in 
the opposite direction, the file marks or grain is laid lengthwise of 



Fig. 10. Die Square 


the die, so that as cross-filing is continued the marks lengthwise 
serve as a guide as to whether the die is being filed straight or not, 
as in e, Fig. 9. 

Clearance . As soon as the webs between the drilled places are 
entirely removed, the clearance of the die should be started. This 
is aided by using a narrow-blade die square of the proper angle, 
Fig. 10. These squares are made by die-makers by filing from 
J^-inch sheet steel, and the blades are about 1| inches long. Some 
use a small block with a straight rod inserted as at b, Fig. 10. When 
the opening is filed so that the scribed outline on the face of the die 
is partly filed away, the filed surface through the die should be care¬ 
fully tested with a knife straightedge to make sure that the cutting 
edge or the top of the opening is not wider than the opening midway 













14 


DIES AND METAL STAMPING 


through the die. By using a fine file or a flat scraper, the filed 
surface can be made very straight. 

Compensating for Bulging. If the shop practice is to have only 
i of a degree clearance, it means that the opening through the die 
will have almost parallel walls. Attention must be paid to these 
walls if the die is somewhat heavy or thick, as there is a bulging 
effect in the opening when the die is hardened, as shown at a, Fig. 11. 
This is probably caused by rapid contraction of the exterior surfaces 
of the die when immersed in the bath, and this contraction com¬ 
presses on a comparatively soft interior, as the interior is red hot. 
To guard against the bulging, the walls of die should be scraped 



( c ) 


Fig- 11. Sketches Showing Method of Compensating for Bulging and of Filing Corners 

slightly concave, as shown at b, Fig. 11. It is readily seen that, if 
the walls are almost parallel and then they bulge toward each other 
during the hardening process, a blank would not pass through the die 
without distortion of the blank. 

Filing Corners. When filing the corners of any die, the file 
must have a smooth edge in order to preserve the corner. Again, 
when filing an angular surface as on the die in question, it is good 
practice to grind the file as at c, Fig. 11; the smooth part sliding on 
the straight part of the die. If the file is not ground to suit the angle, 
the file constantly slides down the angle, and the corner of the file 
mars the finished flat surface at the end of the die. The die files, as 















DIES AND METAL STAMPING 


15 


purchased, seldom are of the right size or shape, and the die-maker 
must grind the file to suit the job. 

Tapping. Referring to the drawing of the die, it is noted that 
there must be four holes drilled and tapped for f—16 screws. As 
the die is of tool steel and also since it is to be hardened, a full thread 
is not necessary, and a 3 ^-inch drill will leave ample stock. After 
all holes are drilled and tapped, the die should be carefully checked 
with the drawing to make sure that all holes are in the die. 

Hardening of Die. The next step is to harden the die. The 
hardness of a die or of any piece of tool steel depends largely upon 
the degree of heat to which the steel is heated, and upon the rapidity 
of cooling. For instance, three pieces of carbon steel, Nos. 1 , 2 , and 
3, are all heated to the same degree of temperature. Piece No. 1 , 
immersed in a bath of oil, would not be as hard as piece No. 2 , 
immersed in water. If piece No. 3 were dipped in a bath of mercury 
and allowed to cool in the bath, the piece would be harder than those 
dipped in oil or in water. Mercury has a higher heat conductivity, 
therefore the heat in the die is dissipated more rapidly with such a 
bath, causing a greater hardness. Starting with the three pieces 
at same temperature and obtaining three degrees of hardness shows 
that it is the bath that plays an important part. 

Corner Protection. Knowing that the dissipation of heat in 
the die plays a prominent part in hardening, we must then guard 
against the effect of holes in the corners of the die. If the die were 
dipped with the tapped holes open, the water or bath of course 
would fill the holes, and the heat would be conducted away faster 
from the corners than if the holes were not there. Therefore, it is 
good practice to fill the screw holes, or any hole that comes near a 
corner, full of asbestos before heating the die; this eliminates some 
of the chances of cracking. If the holes were left open and a free 
circulation of water passed through the holes carrying away heat 
from the die, and the outside surface of the corner were also in con¬ 
tact with or immersed in water, the contraction of the corner would 
be so much more rapid than that of the main portion of the die that, 
when the main portion continued to contract, it would cause a 
tremendous strain between the portion contracted and the portion 
contracting, which would result in a crack. The corners invariably 
drop off if not plugged with asbestos. Fire clay is sometimes used, 


DIES AND METAL STAMPING 


o 

but it is not good practice, for the water in the clay is driven off when 
heating the die and the clay shrinks and drops out of the hole. 

Tempering. Assuming that the die is ready to harden and hav¬ 
ing the screw holes plugged—with a soft machine screw if desired— 
the die is heated slowly and evenly in a muffled fire preferably. A 
blast such as a black smut forge would cause uneven heating of the 
die, which means uneven expansion. If either an open forge or a 
muffle furnace is used, the position of the die should be constantly 
changed to insure even heating, and the face of the die should be 
up. When an even temperature of the desired degree is obtained 
—varying with different makes of steel—the die is gripped by tongs, 
plunged into the bath, and moved slightly up and down, keeping it 
fully submerged at all times. 

The die should not be allowed to remain in the bath, however, 
until it becomes cold, because some parts of the die will contract 
faster than others. When the violent vibration on the tongs ceases, 
the die should be removed and plunged into an oil bath as quickly 
as possible. This is done to allow the heat from the heavier por¬ 
tions to flow into the parts that are cooler, causing a more even con¬ 
traction. The die should be removed from the oil bath before the 
die is cold, it should be drawn to the desired temper immediately 
and, to allow it to cool slowly, should be set on some material which 
is of low heat-conductivity. If a hardened die, while hot, were 
set on a cold mass of steel, the chances are that cracks in the 
die would result. 

Finishing of Die* After the die is thoroughly cool, the oil and 
scale are removed, and the face that is most level is placed against 
the grinder bed and the other face is ground. The bottom of the die 
need only be ground until a true surface is obtained, but the top or 
cutting surface should have several cuts taken across to remove any 
burned metal that may have been caused in hardening and also to 
insure the cutting edge being keen its entire length. 

Laying Out Punch. The next step is to make the punch. 
Assuming that the blanking punch has been machined, the bottom or 
cutting surface is blued in, the same as the die, the punch is clamped 
to the face of the die as at Fig. 12, and the outline of the die is trans¬ 
ferred to the face of the punch. A very slender and sharp-pointed 
scriber must be used, and after the entire outline is scribed, the line 


DIES AND METAL STAMPING 


17 


must be inspected carefully before the clamp is removed. It is 
easy to make an error in transferring the outline, as the die is quite 
thick and the scriber must of necessity be tapering, and the largest 
diameter of the scriber can rest against the die instead of the point 
of the scriber being in contact with the cutting edge of the die. 

If the die has narrow places where it is not possible to scribe 
the line, then the surface of the punch is coated with solder and 
machined level, and the outline of die is transferred by forcing the 
solder into the die. 

Forming of Punch. Shearing Method. The punch is now 
gripped by the shank in the chuck of a milling machine—the shank 
having been turned on the punch for two reasons: to facilitate 
milling the punch to shape; 
and to act as a heavy pilot 
to stiffen the punch on the 
punch plate. After milling 
to within, say, jj% inch of 
the line, the punch is removed 
and the entire cutting edge 
of the punch is beveled 
slightly, and, placing the 
punch in the die opening, 
the punch is forced in far 
enough to obtain the exact 
outline of die. This opera¬ 
tion is called shearing the 

punch. The punch can then be replaced in the chuck of the 
milling machine, and by skillful workmanship all surplus metal can 
be milled away, leaving only a small amount of hand work necessary 
to complete the punch. If the punch is milled after it has been 
sheared in the die, a narrow cutter must be used to remove the small 
and surplus stock. A safer way for the beginner—in fact, many 
experienced die-makers pursue this method is to chip the stock 
away, shear the punch again, and the stock that the cutting of 
the die causes to curl up is again chipped and scraped away, then 
repeating the operation until the punch is fitted the desired depth. 

One point that is essential when shearing a punch in the die is 
to make sure that the punch enters at right angles with the face of 































18 


DIES AND METAL STAMPING 


the die and also that the punch cannot tilt when being with¬ 
drawn. Any tilting when withdrawing will surely break off the 
weak corners of the die. Therefore, it is best to secure the punch 
in the ram of a press and to fasten the die securely to the bed 
when shearing. 

Punches and dies having no weak corners or points can be 
sheared by forcing the punch in the vise but the edge of the punch 
will be rounded off when driving out the punch, if great care is not 
exercised, as one end will invariably drive out ahead of the other. 

In Fig. 13 at a, b, and 
c the punch is shown as 
it appears at the first, 
second, and third shears. 
The punch should not be 
forced in more than J inch 
at a time, as the die does 
not actually cut the metal 
away, but crowds it out, 
and, after a certain 
amount of stock is banked 
up on the punch by the 
crowding or pushing ac¬ 
tion, the stock tears away 
from the punch and deep 
spots will be torn in the 
punch that are below the 
size of the die. For 
chipping away the sur¬ 
plus stock, the chisel 
should be ground so that it does not have a tendency to dig in, and 
the chisel should be struck as shown at c, Fig. 13. 

After each shearing operation and chiseling away of stock the 
surface is smoothed by scraping, d, Fig. 13, and by filing. Only the 
point or end of the file must be used, or else the cutting edge of the 
punch will be filed tapering or too small. The entire surface of the 
sides of punch must be reduced to less than the size of the die, gov¬ 
erned by the thickness of metal to be punched, and the surfaces 
should be made smooth. 



Fig. 13. Chipping Away Surplus Stock on Punch 





















































































































DIES AND METAL STAMPING 


19 


Finishing . If the punch is to be secured to the punch plate 
by screws, the holes are drilled and tapped in the punch by trans¬ 
ferring the holes from the punch plate. 

The punch is now gripped by its shank in a lathe chuck and the 
beveled edge is faced off, leaving a sharp corner or cutting edge, 
after which the punch is hardened. Punches are not made as hard 
as dies, and a deep dark straw color or even purple proves satisfac¬ 
tory for stock that is not tempered by heating and dipping. For 
punching thin soft metals—aluminum, copper, or brass—or paper, 
the punch is generally left soft, for there must be a close fit between 



it and the die in punching thin stock, and when the punch becomes 
dull, which is caused by its rubbing through the material being 
punched, it can be upset or riveted slightly around the edge and 
sheared into the die without taking the punch from the press. This 
insures a perfect fit between the punch and the die which is essential 

on very thin stock. 

After hardening, the punch is attached to the punch plate, and 
the cutting face of the punch is ground by resting the back of the 
punch plate against the bed of the grinder. This insures the face 
of the punch and the back face of the punch plate being parallel. 

Stripper. The stripper is now fastened to the die without the 
guide strip D, Fig. 307, Tool-Making, Fart III, so that the stripper 

































































20 


DIES AND METAL STAMPING 


comes in contact with the face of the die. The outline of the die is 
now transferred to the stripper, and the stripper then is removed and 
the opening drilled and filled, much the same as for the die, except 
that the opening in the stripper is generally made somewhat larger 
on large blanking punches. 

Die Shoe. The adjustable die shoes shown in Figs. 308, 309, 
310, and 311, Tool-Making, Part III, are designed more for a jobbing 
shop where quick changes are made, that is, where only a few blanks 
of each kind are made at a time; but for continued daily production 
it is better to fit the die tight in a recess in the die shoe, as in Fig. 14, 
and to have a separate die shoe for each die. The first cost of mak¬ 
ing the die shoe for each die is soon wiped out by the saving of the 
pressman’s time in changing the dies from one shoe to another. 

SUB=PRESS DIES 

Typical Features. Plain blanking dies as described this far are 
of the simpler type and are used only where a variation in blanks 
is permissible, for any die that allows the blanks to pass clear through 
is given clearance, and each time the die is ground the die becomes 
larger. With sub-press dies—sometimes called compound dies—the 
outside diameter or size of blank does not change, as the dies are 
made without clearance, for the blank only enters the die about half 
the thickness of the stock being punched, then the blank is forced 
back into the strip. 

Before entering upon the making of a sub-press die, it is well to 
thoroughly understand the working of this type of die which in some 
instances is quite complicated. The term sub-press die means that 
the punch and die are mounted in a sub-press, or, to make it plainer, 
the punch and die work within a frame which has a babbitted bearing 
to guide the plunger to which the blanking die and piercing punches 
are attached, and this frame or sub-press is in turn actuated by a 
power press. 

Fig. 363, Tool-Making, Part III, is an excellent illustration of 
the working principle of sub-press construction in its simplest form. 
Bear in mind that this die is a sub-press in principle only. Referring 
to this illustration it is noted that the blanking die A is mounted 
on the upper portion, which is characteristic of all sub-press con¬ 
struction. The blanking punch B also contains the piercing die C , 


DIES AND METAL STAMPING 


21 



and inside the blanking die A and surrounded by the upper stripper 
h is the piercing punch D. The lower stripper F surrounds the 
blanking punch. 

Operation. In opera¬ 
tion the stock is placed 
on top of stripper F y and 
as the upper portion de¬ 
scends blanking punch B 
enters blanking die A, 
causing stripper E to 
recede. At the same time 
that the blanking punch 
enters the die, piercing 
punch D enters piercing 
die C in the blanking 
punch. In fact, all parts 
interlock. The blank is 
forced into die A, and the 
scrap punching passes down through hole C. As the upper section 
ascends or separates, strippers E and F move toward their original 
positions, due to spring 
pressure, just as fast as 
the upper section as¬ 
cends. The result is 
that the blank is forced 
back into the strip by 
both strippers. 

While the die shows 
only the principle and 
would blank a washer at 
each stroke, it can be 
readily seen that the 
blanking punch and die 
can be of any shape and 
that a number of piercing punches may be employed. Any one 
of the sample punchings shown in Fig. 379, Tool-Making, Part III, 
is made at one stroke, and the clock plate shown has thirty-four 
separate piercing punches. 


























































































































22 


DIES AND METAL STAMPING 


Making Press Body. To make a sub-press die to produce the 
blank shown in Fig. 15—the balance wheel of a clock—looks at first 
glance to be a difficult job, but in reality it is simple, and the die 
can be made without touching a file to it except to remove a few 
burrs. The sub-press base, Fig. 16, is made by first planing the 
bottom, then, strapping to a lathe faceplate, the top face is turned 



Fig. 17. Sub Press parts: a —Blanking Punch and Piercing Die; b —-Lower Stripper; c — 
Press Frame Cap; d —Plunger; h —Punch Holder;/—Blanking Die; M —Upper Stripper; 
o —Crossbar Punch; P —Section of Blanking Punch; Q —Section of Assembled 

Blanking Punch; R —Piercing Punch 


level and the recesses ab are bored. The recess a, Fig. 16, is the 
seat for the blanking punch a. Fig. 17, and the large recess b, Fig. 
16, receives the lower stripper b , Fig. 17, for the blanking punch. 

The frame o'. Fig. 18, is next machined by gripping the end b 
in a lathe chuck and facing off the bottom, and boring the recess to 
a good push fit for the outside of flange c. The inside of the frame 
















































































DIES AND METAL STAMPING 


23 


must be bored tapering, but not while gripped in chuck, for the 
frame is thin and that portion gripped is slightly distorted, and 
the inside it would not be round when the chuck pressure is released. 



Fig. 18. Details of Sub-Press Punch and Die for Fig. 15 

The base, Fig. 16, is now drilled as at del , the frame is placed 
on the base, and the holes dd are transferred to the frame. The 









































































































































































24 


DIES AND METAL STAMPING 


holes in the frame are tapped, the frame is removed, and the holes 
are slightly countersunk to remove all burrs to insure the frames 
resting level on the base. The base is then returned to the face¬ 
plate of the lathe, and the flange c indicated to run true—the base 
must be attached to the faceplate so that both, if possible, or at 
least one of the screw holes in the base comes opposite a slot in the 
faceplate. The frame is then pushed on the base and the screws 
put in from the back, securely holding the frame to the base. In 
this position the inside taper bore of the frame is bored, and the 
end is threaded to fit cap c, Fig. 17—previously threaded—at the 
same setting, and the end of the frame is faced off. 

After the hole is bored a splining tool is placed in the tool post 
and the spindle locked by means of the back gears, and a groove is 
splined lengthwise of the bore by sliding the carriage back and forth. 
Light chips must be taken until a groove about yg- inch deep is made. 
The spindle is rotated one-half or one-third and one or two more 
grooves are splined. These grooves are simply to prevent the 
babbitt from turning, and the accuracy of the spacing is immaterial. 

The cap c, Fig. 17, is now screwed on the end of the frame, the 
edges smoothed by turning, and the hole bored to the desired diam¬ 
eter, which should be a sliding fit for the plunger d, Fig. 18. This 
completes the lathe work on the base, frame, and cap. 

Making Plunger. The button e, Fig. 18, is next made on cen¬ 
ters and the thread chased. Then the plunger d is made; being 
roughly turned on centers to say, within y^ inch of finish size. The 
long hole in the plunger is now drilled, bored, and threaded, by 
holding one end in the steady rest and the other end on the live 
center, a lacing in connection with a lathe dog being used to hold 
the plunger against the live center. When using a lacing, the face¬ 
plate should be loosened several threads, and, after the dog on the 
end of the plunger is securely tied to the faceplate, the plate is 
screwed against the shoulder of the spindle, which tightens the 
lacing and securely holds the plunger against the live center. After 

the hole is bored and threaded the button is screwed into the end 
« 

of the plunger, and, placing the dog on the button, the plunger is 
turned perfectly straight and smooth and so it fits the hole in the 
cap. The end of the plunger is turned | inch smaller in diameter 
for a distance of 1 inch as in d, Fig. 17, and also in Fig. 18. 


DIES AND METAL STAMPING 


25 


The lathe spindle is now locked and four unequally spaced 
grooves/ are cut in the plunger the entire length but not deep enough 
to touch the reduced diameter at the end of the plunger. The grooves 
are to act as guides when babbitt is poured around the plunger, and 
the object of unequally spacing is to prevent returning the plunger 
in the babbitt bearing in any position but that in which the punch 
and the die line up. 

The steady rest is now brought to bear on the reduced diam¬ 
eter, the recess g is bored for the punch holder h , and the shoulder 
i is turned to the desired diameter to act as a centrally locating 
member for the blanking die j. The diameter of the plunger is of 
course governed by the outside diameter of the blanking die which 
is attached to plunger, for it is obvious that a die larger than the 
plunger could not be withdrawn from the frame after the babbitt 
surrounds the plunger. 

The points to be observed in making the plunger are: absolute 
straightness; grooves perfectly straight and free from chatter marks, 
and each one of a uniform depth its entire length; and the finished 
plunger absolutely free from blowholes caused by casting. 

Making Small Parts. Blanking Die. It is immaterial in which 
order the remaining parts are made, as they will be only partly 
finished when turned to size in the lathe. The blanking die j, Fig. 17, 
should be made from the end of a bar gripped in a chuck and the large 
diameter of the die should be on the outer end, as in Fig. 19a, so 
that the recess can be fitted to the step on the plunger. The hole 
k , Fig. 17, should be bored at the same setting, and the diameter of 
the hole must be smooth and of the exact diameter desired at a, 
Fig. 15. The die is cut from the rod with a cutting-off tool in the 
lathe. 

The piercing-punch holder h, Fig. 17, is also turned on the end 
of the rod, and the step L fitted to the recess in the end of the plunger. 
The upper stripper M, Fig. 17, should be turned on centers as at 
b, Fig. 19, and left on the piece of rod, for the next operation on the 
stripper is to mill to form the projections on the balance wheel, as 
shown at M, Fig. 17. 

Blanking Punch. Instead of making the blanking punch a, 
Fig. 17, solid, then filing out the recess at each side of the crossbar, 
which would be a difficult job, the blanking punch is turned in the 


26 


DIES AND METAL STAMPING 


manner shown in a , Fig. 19. The hole N is bored smooth to the 
exact diameter of b, Fig. 15, and the outside of the punch is turned 
to exactly the same diameter as c, Fig. 15. The large diameter of the 




Fig. 19. Broaches and Cutters Used in Making Fig. 15 

blanking punch is turned to fit the recess a in the base, Fig. 16, 
after which the punch is cut from the rod. 

A die to produce the balance wheel cannot be readily ground 
to shape after hardening, therefore, an oil-hardening make of steel 
should be used, which will eliminate many chances of the die 
changing shape and will permit of machining the parts to exact size 
while soft. 















































































































DIES AND METAL STAMPING 


27 


The piece o, Fig. 17, which is milled to the shape of the cross¬ 
bar and when completed is inserted inside of the blanking punch, 
is turned on the end of the rod with the small diameter on the end 
of the rod. The diameter of the small end must be left inch 
larger than the hole through the blanking punch, for the blanking 
punch is splined to a depth of inch on each side, as in the 
enlarged section at P, Fig. 17, to position the ends of the cross¬ 
bar as shown in the assembled sketch Q of the end view of the 
blanking punch. 

Use of Special Cutters. Before milling the spaces on the 
stripper and the blanking punch, it is necessary to make a number 
of broaches, c, Fig. 19. The number of broaches being governed by 
the depth of the projections or teeth. The broaches are turned on 
centers and the end pilot of each broach is made the same diameter 
on all broaches, and the pilot must be a good fit in the hole of the 
blanking die to be broached. The broaches are made in steps as 
shown, each step increasing in diameter by .005 inch. Chip clear¬ 
ance is provided at r. The broaches are numbered 1, 2, 3, etc., 
and the first step on broach No. 2 is made .005 inch larger in diam¬ 
eter than the last step on No. 1, and so on. The last step of the last 
broach has the same outside diameter as at c, Fig. 15. 

A formed milling cutter s , Fig. 19, is now used to mill the spaces 
on the broaches, upper stripper, and the blanking punch. The 
milling cutter is set as nearly central with the center of the dividing 
head of the miller as possible. Then a test piece, which may be any 
scrap piece of steel or brass, is gripped in the chuck of the dividing 
head and milled as at t, Fig. 19. The dividing head is then rotated 
one-half of a complete turn, which brings the milled portion of the 
rod on the bottom side. Without disturbing the cross-movement 
of the table the milling machine knee is raised so that the milling cut¬ 
ter can be matched with the milled shape in the rod. If the formed 
cutter is not centrally located, it is readily noted, for when the 
milled rod is turned one-half revolution, the milled surface when 
matched with the cutter shows just double what the error is, as at 
u, Fig. 19, and by moving the table one-half the space shown between 
the milled form and the cutter and then milling a new place in the rod 
and repeating the operation of revolving the dividing head one-half 
revolution, the cutter can be very accurately set. 


28 


DIES AND METAL STAMPING 


Having set the milling cutter central with the head or centers, 
the broaches are milled, and, without disturbing the setting of the 
milling cutter, the blanking punch is also milled, as is likewise the 
stripper M, Fig. 17. The blanking punch is held while milling on a 
special arbor having a shoulder as at v, Fig. 19, to grip the flanges 
of the punch and the stripper, as the small bearing surface in the 
straight hole in the blanking punch or the stripper would not be 
sufficient to prevent turning on an ordinary arbor when milling. 
The broaches are hardened, and then ground on the face by revolv¬ 
ing them between centers and using a saucer or cup form of 
emery wheel. 

The die j, Fig. 17, is now placed on a level surface in a power 
press which will permit the broach passing through the die. Enter¬ 
ing the pilot of No. 1 broach in the hole in the die, the surface of the 
die is flooded with heavy oil and the broach is forced through the 
die. The succeeding broaches in their order are forced through in 
the same manner. The screw and dowel holes are put in the die, 
which completes it except for hardening. 

The inside piece o, Fig. 17, of the blanking punch is milled with 
a formed cutter as at/ir, Fig. 19. At the same setting of the miller 
the crossbar for the inside of the stripper is milled, but this bar is 
made two or three thousandths thinner than the crossbar for the 
blanking punch. The blanking punch a, Fig. 17, is now clamped, 
face out, to the faceplate of the dividing head, a splining tool is 
secured to the arbor of the miller, the spindle of the miller is locked, 
and the two small recesses are splined the entire length of the straight 
portion of the hole in the punch. The recesses are to receive the 
ends of the crossbar punch o. Care must be exercised in setting 
the splining tool absolutely central with the center of the dividing 
head, and the blanking punch must be indicated by the hole so that 
it is central with the head of the miller. 

Fitting Piercing Punches and Dies. It must be remembered 
that sub-press punch and dies do not enter when in use, therefore all 
parts can be made straight except the scrap punching dies. Clear¬ 
ance must be given to that part of the die where the scrap pieces or 
punches pass through, and when the pierced hole is irregular in 
shape, it of course is filed out. The piercing dies, however, as a 
rule are too small to permit the use of a die square, and for straight- 


DIES AND METAL STAMPING 


29 


ness of side of filed openings or piercing dies the die-maker must 
depend upon skillful filing. In order to determine whether or not 
the piercing die has clearance on its entire length, babbitt is 
employed. The die is warmed slightly and laid face down on a piece 
of paper which in turn is on a flat surface, and the opening is filled 
with molten babbitt. When the babbitt is cool it should drop 
freely from the die if the die has proper clearance. When forced 
out, there will be polished streaks on the babbitt indicating just 
where the die has insufficient clearance. 

As to fitting the punches of a sub-press die the same method is 
employed as in connection with the gang die shown in Fig. 37— 
that is, making and inserting the round piercing punches first 
and using them as guides, then as each irregularly shaped pierc¬ 
ing punch is fitted it is left in the punch plate to act as an 
additional guide. 

In making the piercing punches, they are attached to the punch 
holder and the holder plunger, the frame is assembled and babbitted, 
and the piercing punches are sheared while the plunger is 
guided by the babbitt bearing. The upper stripper, that 
works inside the blanking die, is blued on its face, and, 
removing the piercing punches from the plunger, the stripper 
is placed in the die, the plunger is replaced in the babbitt 
bearing, the stripper brought in contact with the blanking 
punch, and the outlines of the piercing dies are scribed on 
the face of the stripper. The stripper is then drilled out 
and filed to the lines. The punch plate containing the 
piercing punches may be tried from the back of the strip¬ 
per, and the openings in the stripper filed until the piercing 
punches pass through to the face of the stripper without 
being forced. 

Placing Round Holes. For transferring any round hole not 
centrally located from the templet to the punch holder or to the die, 
a small prickpunch, Fig. 20, is turned up, one for each hole, and the 
prickpunch must fit the hole. At the same time that the body of 
the prickpunch is turned to fit the hole the small point b is turned. 
The prickpunehes are hardened, and the templet is clamped or held 
to the punch plate by a few small drops of solder, the prickpunch is 
entered in the corresponding hole in the templet and lightly tapped 



Fig. 20. 
Prick- 
punch 



30 


DIES AND METAL STAMPING 


on the end with a hammer. After the centers of all holes have been 
prickpunched the punch plate is strapped to the lathe faceplate, 
the prickpunch mark indicated, as shown in Fig. 21, and the holes 
carefully spotted and drilled. 

The holes should be bored if possible. It is not safe to trust a 
drill starting centrally in a carefully made spot. Neither is it safe 
to trust a reamer to size a hole, even if the hole has been bored nearly 
to size, for a dull tooth on the reamer, or a soft tooth, or a hard spot 
in the steel at the edge of the hole, or a burr may cause the reamer 



Fig. 21. Method of Locating and Indicating Prickpunch Mark 


to deviate slightly. The only dependable method is to bore the 

hole with a single-pointed cutting tool—it does not matter whether 

the tool is stationary and the work revolves, or the tool revolves 

and the work is stationary. 

«/ 

Use of Master Plate. If the die being made is for a product that 
will be used year after year, or if the quantity of the product is such 
that new dies must be frequently made, it is good practice to make 
a master plate. This is done by machining a |-inch plate of soft 
steel or cast iron perfectly parallel, and of the same size as the die, 
then, when making the die, the plate is fastened to the face of the 

























DIES AND METAL STAMPING 


31 


die and the holes are put in as above described or by the button 
method through the master plate and die, the holes in the master 
plate being bored one size. 

When making the next die the master plate is attached to the 
back of the die, a soft-steel center in the lathe is turned to fit the hole 
in the master plate, the master plate to which the die is attached is 
wrung on this soft center, and the die is clamped to the faceplate, 
and spotted, drilled, and bored. As the soft center in the lathe was 
turned, it therefore is central with the lathe spindle, and, as the 
center fits the hole in the master plate, it is obvious that a hole 
drilled and bored in the die will be directly in line with the hole in 
the master plate. This is the most accurate method of transferring 
holes. Great care must be exercised when transferring holes from 
a templet or a master plate to have the proper side of the plate 
against the die. For instance, in transferring from a templet to a 
die, one face is against the die, but, when using the same templet to 
transfer to the punch plate, the opposite face of the templet must 
be against the punch plate. This is caused by the face of the punch 
plate being up when transferring the holes, but down when the 
punch plate is in use. 

Assembling Parts. The blanking punch and die, and the 
crossbar punch o, Fig. 17, for the blanking punch, are hardened, the 
bar punch is inserted in the blanking punch, and both punches are 
screwed to the base. The piercing punch R, Fig. 17, which is evenly 
coated on the face with solder is attached to the punch holder and 
the punch holder is attached to the end of the plunger. The blank¬ 
ing die is attached to the plunger by screws and dowels, but a thin 
parallel washer, or ring, a trifle smaller in diameter than the outside 
diameter of the die and about ^ inch thick is placed between the 
blanking die and the plunger to cause blanking die j to protrude 
-L- inch beyond the face of punch R so that blanking punch a can be 
entered in the blanking die. The frame is now fastened to base, 
care being exercised that there is no grit between the bottom of the 
frame and the top of the base. 

The plunger is placed inside the frame, and the punch and die 
entered. The frame cap c, Fig. 17, which fits the plunger is screwed 
on the end of the frame, which locates the plunger centrally in the 
frame. The entire mass is now inverted, and, resting the cap on 


32 


DIES AND METAL STAMPING 


parallels the frame is slightly heated with a gas torch, and the molten 
babbitt is poured in the frame. Putty is used at the die end of the 
plunger to prevent the babbitt leaking. The whole mass is allowed 
to become thoroughly cooled before disturbing. When cool, the 
inside outline of the blanking punch is forced into the soft solder on 
the face of the piercing punch. 

The plunger is now removed from the frame, piercing punch 
R, Fig. 17, is removed from the plunger, and slot S is milled or 
shaped to the line on the solder. After milling very close to the line 
the parts are reassembled and the punch is sheared far enough to 
obtain a good impression on the steel punch. The punch is now 
carefully milled or filed to remove all marks of shearing. 

/ 

SECTIONAL DIES 

Advantages. When dies are large or when there are many 
weak projections, it is good practice to make the dies in sections. 

One reason is that the 
individual pieces of a large 
die can be machined to 
shape easier. Another 
reason is that a long die 
or a large die would dis¬ 
tort appreciably when 
being hardened, which 
would mean that the die 
could not be finished to 
exact size, but that a 
considerable amount of 
stock must be left on the 
large solid die in order 
to grind to shape after 
hardening. In the case of weak projections in a die, if the die is 
left solid and one point breaks, the entire die is ruined, whereas, 
with a sectional die, that part containing only the broken portion 
can be removed and a new one made at a small cost. 

Laying Out Die. The procedure in making such a sectional die 
as in Fig. 325, Tool-Making, Part III, would be to machine the two 
strips as in Fig. 22, herewith, and, clamping them together, to lay 





C' -* ' 


--__ 



(b) 

Fig. 22. Clamping Sectional Die for Outlining 














DIES AND METAL STAMPING 


33 


out the outline from a templet or drawing in the same manner as 
the die in Fig. 4 was laid out. 

Shaping of Die. The parting line of the two halves should 
come in the center of the scribed outline. The operation of drilling 
along the line as in the case of the die in Fig. 4, would be useless, 



Fig. 23. Shaping Die, Showing Method of Obtaining Clearance 


for the end hole can be drilled, and reamed tapering, then each half 
in turn may be gripped in a shaper vise, Fig. 23, and, by placing a 
small wire or a strip of folded paper of the right thickness to tilt 
the strip at the desired angle for clearance, then placing, say, a 
J-inch rod at the mid height of the jaws, the opening in the strip 





























































































34 


DIES AND METAL STAMPING 


can be easily machined to size and the clearance can be machined 
at the same time. 

Shearing Precautions. Several dowel holes are drilled in each 
strip, if possible, in addition to the screw holes, for fastening to the 
die shoe, and, after hardening and grinding the die strips, the die 
shoe is machined to receive the two strips. A snug fit is necessary. 
The dowel holes are now transferred from the die strips to the die 
shoe, and the dowels are inserted. There is always more or less 
spring to a sectional die when shearing the punch. Care must be 
exercised in not attempting to shear too much stock, as the dies 
will spread. 

Fig. 24 shows the method employed in making a small sectional 
die of simple design having weak projections. It is obvious that 
weak points, such as shown on this die, would not withstand the 



Fig. 24. Making Sectional Die with Weak Projections 


pressure necessary to shear much stock. Therefore, when shearing 
a punch having such points, always remove the stock by scraping 
or filing and do not allow the points in the die to shear the punch. 
Great care also is necessary in withdrawing a punch from a die of 
this character when shearing the punch. 

Hardened and Ground Sectional Type 

Construction Requirements. The cores for coils and armatures 
are made up of variously shaped laminated soft-iron punchings, 
which, as a rule, must be extremely accurate. The iron sheets are 
rolled hot, producing a hard scale or oxide which causes severe wear 
on punches and dies. The dies must be frequently ground, as burrs 
on punchings are prohibited, and if the dies were given clearance 
each grinding would produce a larger punching. Therefore, due to 
intricate shapes that must be exact and the fact that the wear on 
























































































DIES AND METAL STAMPING 


35 


the dies is severe, the dies are invariably made of the sub-press con¬ 
struction and also made up of pieces, the latter being ground all 
over to size after hardening. There is no clearance given these dies 
and they are known as sectional 
or built-up dies. 

Intricate Shapes. When the 
die is of extremely intricate shape, 
having a great number of pierced 
slots, Fig. 25, the usual method 
is to make a single punch and 
die, and, by the use of an accu¬ 
rate indexing fixture which holds 
the blank, the notches are pierced 
one at a time and the indexing 
done automatically by the stroke 
of the press. One operator can 
attend to several presses. The 
object in indexing and using a single piercing die is to eliminate the 
high cost of making a die to produce the blank in one stroke and also 
to eliminate the cost of repairs, for if one small point on such a die 
should break it would render the entire die useless until repaired. 




The punching shown in Fig. 26, while extremely accurate, is 
of a comparatively simple design, but the method of making is the 
same as for dies for more intricate shapes. The punchings are built 
up as in Fig. 27, and every other one is reversed, so that the error 
must be slight, for in reversing the blanks the error is doubled. 










































DIES AND METAL STAMPING 


3j 


Making of Die. Division in Pieces. When laying out a built- 
up die that is to be ground to shape and size after hardening, the 



Fig. 27. Method of Mounting Punchings Shown in Fig. 26 



b 

Fig. 28. Two Methods of Making Sectional Die 

sections should be as free from internal corners as possible, as it is a 
difficult job to grind a good sharp inside corner. For instance, 
referring to Fig. 28, it would be easier to make and grind the four 


















































37 


DIES AND METAL STAMPING 

pieces, as at a,, than it would be the two pieces with inside corners, as 
at b. Therefore, the division of the die at hand for sections requires 
considerable study. 

Referring to Fig. 29, it will be seen that the division lines are 
so placed that there are no corners in any one piece and that each 
piece is comparatively easy to make. Instead of laying out from a 
templet, or roughing out the pieces and placing them in position, 
then laying out the outline on the pieces, a better way is to make 



Fig. 29. Building Up Die for Punching Shown in Fig. 26 


each piece by measurement. The pieces a and i are simple end 
pieces, perfectly straight, and can be eliminated from the descrip¬ 
tion of making. Referring to piece b, Fig. 29, we find by totaling 
the dimensions on the drawing, Fig. 26, that the piece is 2 ^ inches 
wide and. that the angle is 45 degrees. This piece is carefully 
planed or milled to exact shape, but, say, .010 inch is left on each 
surface for grinding. Piece c, Fig. 29, is important, as the width 
governs the length of the end of the punching. Referring to the 
drawing, Fig. 26, we find this width to be \\ inches, and .010 inch is 
left op each surface for grinding; and so on, until all pieces are 





























38 


DIES AND METAL STAMPING 


roughed out to within grinding allowance. The edges and bottom 
of all pieces must be at right angles even when in rough size. 

Doiveling Hardened Pieces. After all pieces are roughed out 
the screw and dowel holes are drilled. The dowel holes, however, 
are drilled, and then tapped with a fine-pitch thread; if a f-inch 
dowel is used, the holes can be tapped, say, J—32 pitch. The object 
of tapping the dowel holes is to permit screwing in tight-fitting soft- 
steel plugs after the pieces have been hardened, following which the 
plugs are dressed off flush with the top and bottom of the piece. 
Then after all pieces are ground to size and securely fastened in 
proper place by means of the screws, the dowel holes are drilled 
and reamed through the soft-steel bushings or plugs and into the 
die shoe. This is better practice than to drill and ream the dowel 
holes in the pieces before hardening, for, after hardening the pieces, 
the holes are slightly distorted; but, granting that the holes remained 
true, it becomes necessary to transfer the holes to the die shoe, and 
in order to do this a drill is used, using the dowel holes in the hard¬ 
ened pieces as a jig. The drill used must of necessity be somewhat 
smaller than the hole in the hardened piece, possibly not more than 
one or two thousandths, but whatever the difference between the 
drill and the hole is, that difference can cause an error in the align¬ 
ment of holes in the hardened piece and in the die shoe, as the drill 
can bear against one side of the guide hole, drilling the hole off 
center. Using the hardened pieces for a guide prohibits the use of 
a reamer, for, in order to have the reamer size the hole in the die 
shoe and to bring the hole in the die shoe absolutely in line with the 
hole in the piece, the reamer must fit the hole in the hardened piece, 
which of course would ruin the reamer. The greatest objection to 
using the holes in the hardened piece for a guide for the drill and 
reamer is that the holes are invariably distorted during the hardening 
process. 

Having drilled and deeply counterbored all screw holes, and 
drilled and tapped all dowel holes, the pieces are hardened, but, as 
the die is to cut iron having scale, the die is left harder than for 
ordinary sheet steel. 

Grinding Pieces. The first grinding operation is to take a chip 
across a temporary bed, or the grinder bed itself, or the face of a 
magnetic chuck to insure the surface being parallel with the travel 


DIES AND METAL STAMPING 


39 


of the cross-slide and the travel of the bed. The pieces are examined 
on the bottom side to make sure no burrs are protruding or scale 
adhering to the pieces that would tilt them, for there is only an. allow¬ 
ance of .010 inch to remove, and a slight tilt might be sufficient to 
prevent the pieces cleaning up all over. All pieces are then placed 
on the newly finished bed and waxed to the bed, unless a magnetic 
chuck is employed. After all pieces are ground on the top side, 
the wax is thoroughly removed from the bed, the pieces cleaned, 
and the surfaces just ground are waxed to the bed, and the bottoms 
then ground. All pieces now are of uniform thickness and parallel. 

An angle iron, or, what is better suited for this class of work, 
a hollow square, absolutely square in every position, Fig. 30, is now 



Fig. 30. Hollow Square Used for Holding Pieces for Grinding 


waxed to the surface of the newly machined bed. In either case the 
angle or hollow square must be absolutely square and must be 
waxed to the bed so that the vertical face of the angle is absolutely 
parallel to the line of travel of the bed. This is accomplished by 
clamping an indicator to the side of the wheel. Do not trust a 
square against the machined surface of the uprights of any machine, 
if the surface of the work must be parallel with the line of bed travel, 
for by so doing we are trusting to the accuracy employed by the 
machinist who built the machine: eliminate all chance. 

Assuming that the hollow square is correctly located and waxed 
to the bed, the first piece to be ground can be a, Fig. 29. By clamp¬ 
ing the piece to the hollow square and using the indicator attached 
to a surface gage, the piece can be positioned parallel with the surface 


































40 


DIES AND METAL STAMPING 


of the bed by testing each end of the piece for height, using the 
indicator. The piece need project above the hollow square only a 
slight distance, say yg- inch. As the top and bottom of piece a are 
perfectly parallel and the hollow square is perfectly square—at 
right angles—it is obvious that when the upper face of piece a is 
ground, the face will be at right angles with the top or bottom. 

Piece b, Fig. 29, is clamped to the hollow square, as in Fig. 31, 
and the end of the piece is lined up with the bed by placing a square 
on the bed. The use of a square will be found accurate enough for 
the grinding of the first edge, but, after one edge is ground, if the 
remaining edges are trued up at right angles with each other by 
holding the base of a square against the vertical edge of the work, 
and using an indicator clamped to the emery-wheel and with pointer 



sliding along the blade of the square, as in Fig. 32, the work can be 
made more accurate than by holding the blade against the work 
while the base of the square is on the bed of the machine. After 
the first edge has been ground, the piece should be tested, as in 
Fig. 33, to prove that the side of the hollow square is at right 
angles with the bed, as grit can get under the hollow square unless 
extreme care is exercised. The piece b now being ground on two sides, 
its succeeding sides or edges may be ground by a similar procedure. 

Each piece must be ground on the edges as above described, 
always using the indicator to square up the work, for the use of 
parallels is not safe. A slight nick on a parallel or a piece of grit or 
even a slight taper of the parallels would of course be transferred 
to the work. 









































DIES AND METAL STAMPING 


41 


Placing Die Pieces on Shoe. After all pieces have been ground 
to exact dimensions, they are attached to the die shoe and placed 
in position by soft test pieces that have been machined the right 
thickness. These test pieces are placed in the opening of the die, 
and the die pieces are brought to bear against the test piece, in 
which position the hardened pieces are securely fastened in place by 



screws. After tightening the screws the die should be gone over 
again to see if some piece had moved a trifle when tightening the 
screws; then drill and ream for dowels. 

Attaching Piercing Punches. While the die pieces are attached 
to the die shoe, the die shoe is in turn attached to the punch holder, 
as the die in all sub-press construction where piercing punches are 
employed in conjunction with blanking operates as the upper mem¬ 
ber. It will be noted that the piercing punches for the holes shown 
























42 


DIES AND METAL STAMPING 


in Fig. 26 have not been inserted in the die as yet, for the reason 
that it is easier to put the piercing punches in place after the die 
is complete. This is accomplished by drilling holes in the die shoe 
approximately where the punches will come but by making the holes 
a trifle larger than the larger diameter of the punch and then insert¬ 
ing the piercing punches in small individual punch holders, these 
punch holders in turn being attached to the back of the die shoe, 
the punches can be properly located from the holes in the blanking 
punch by shifting the individual holders one way or another and may 
be securely screwed to the die shoe when the punches are in proper 
location. The individual punch holders can be inserted in recesses 

in the die shoe, or can be 
screwed on top of the die 
shoe, and the punch ho lder 
recessed to clear them. The 
locating of punches in this 
manner eliminates considerable 
boring of a very accurate 
nature. Another method of 
inserting the piercing punches 
in the upper half is to com¬ 
plete the blanking punch, then 
the die, and, by entering the 
punch in the die, the holes in 
the blanking punch which are 
the piercing dies can be trans¬ 
ferred to the die shoe. This 
is not as accurate, however, as the adjustable punch-holder method. 

Making Blanking Punch. The blanking punch is also made up 
of pieces and is more difficult to make than the die, for the holes in 
the blanking punch which are the piercing dies must be very accu¬ 
rately located and bored, and, after hardening the punch pieces, the 
punch pieces are ground to shape and dimensions from the holes. 

Measuring from Piercing Holes . The holes are put in the soft 
pieces of the punch after the pieces have been roughed out to within 
the grinding allowance. After hardening, the holes are thoroughly 
cleaned, and taper plugs are turned of soft steel to fit the tapered 
holes. That portion of the plugs, however, that extends beyond 



Fig. 33. Proving Accuracy of Work after 
First Edge Is Ground 











DIES AND METAL STAMPING 


43 , 

the face of the punch, Fig. 34, is straight and all diameters must be 
exactly alike. When grinding the punch sections, the plugs rest 
on the hollow square or on the top of the angle iron to insure the 
edge being ground parallel with the hole, and the method of meas¬ 
uring for proper thickness is as shown in Fig. 34. The small pro¬ 
jecting plugs must be of exactly the same diameter, but the actual 
diameter is immaterial. The punch thickness is f inch, and, assum¬ 
ing that the projecting ends of the plugs in the holes are .250 inch in 



diameter, it means in this instance that the distance A must be 
one-half the thickness of the punch plus one-half the diameter of 
a plug or .375 + .125 = .500 inch. 

Discrepancies. When a portion of a punch is at an angle, the 
grinding of the punch sections requires considerable care and skill 
due to the fact that discrepancies on abutting ends of punch sections 
will greatly multiply themselves at the extreme ends of the punch 
as in Fig. 35. A slight opening as at a, Fig. 35, is permissible. 

The object in making the punch thin, then attaching it by 
screws to the soft-steel punch block a, big. 34, is for rigidity. It 




































44 


DIES AND METAL STAMPING 


would be easier to make the punch as in Fig. 36, leaving enough 
stock to grind to size, then grinding out the holes to proper location, 
but the face of the punch that bears against the holder is too narrow 



Fig. 3'>. Sectional Blanking Punch, Showing Exaggerated Opening for 
Making Adjustments and Completed Sections 


for a working seat, and any miscut by the press operator, or a piece 
of scrap punching adhering to the sheet being punched, would 



Fig. 36. Punch Easier to Build than Fig. 35 but Not So Satisfactory 

cause the punch to spring to one side. This causes the edge of the 
punch to strike the edge of the die, and a broken member or a sheared 
punch is the result. 

GANG DIES 

Accuracy Required in Making. By referring to Fig. 341, Tool- 
Making, Part III, it will be noted that in addition to the blanking 
punch there are two piercing punches attached to the same holder. 
Since these piercing punches, as well as the blanking punch, must 
















































































































DIES AND METAL STAMPING 


45 


be in perfect alignment with the dies, the method of procedure is 
different from that in connection with the simpler dies, and a gang 
die requires careful laying out. Assuming that the die we are about 
to make is the shape and type shown in the illustration referred to, 
we will first consider the different methods which could be employed 
to make the die, and then select the most practical one. 

Drilling and Filing Method Precluded. A true radius is shown 
at each end of the blanking die E. If we were to drill holes just 
inside the lines and to broach out the center piece as described for 
the die of Fig. 4, difficulty would be experienced in filing the ends, 
as it is extremely difficult to file a true radius. Besides, this method 
would entail considerable hand work, and it is good practice to elim¬ 
inate hand work as far as possible. The drawing, Fig. 37, calls for 
a positive distance be¬ 
tween the two piercing 
dies, and also calls for a 
blank 2.250 inches long. 

It is shop practice that, 
when dimensions are 
given in thousandths of 
an inch, the dimension is 
important and must be 
adhered to within a thou¬ 
sandth. When given in 
four decimals, finer accu¬ 
racy is required, but when given in fractions, a variation of several 
thousandths is permissible. Therefore, the length of the blank being 
important, and the ends of the blank being of a true radius, the 
drilling and filing method is precluded. 

Errors of Drilling and Counterboring Method. The location of 
the holes and blanking die could be laid out with a height gage, and, 
where the lines cross, fine prickpunch marks should be placed, from 
which as starting points the holes could be drilled and counterbored 
to proper depth for bushings or counterbored clear through for the 
piercing die proper. But there are several chances for errors in this 
method: (1) The prickpunch mark may not be placed exactly 
at the intersection of the lines. (2) The drill may not have started 
exactly in the center of the prickpunch mark, or granting that it 



Fig. 37. Drawing for Gang Die Blank 



























46 


DIES AND METAL STAMPING 


did, the drill can run , which is the shop term applied to a drill leaving 
its intended travel or path. (3) The holes must be given clearance, 
and, since they are drilled, the taper reamer is the logical method. 
We have already shown how a taper reamer will start on an 
angle carrying the center distance of holes one way or another. 
(4) When drilling and counterboring the two end holes to form the 
radial ends of the blanking punch, the prickpunch can be out, the 
drill can start wrong, and the pilot of the counterbore in not fitting 
the hole can change the center distance and the counterbore may 
cut too large even though it measures the proper diameter. (5) The 
final opportunity for error is in the reaming of holes for clear¬ 
ance. All these chances for errors must be considered, and here 
again is where a careful study of the drawing would show that the 
ordinary easy method cannot be used. 

Approved Method of Making. The proper sequence of opera¬ 
tions to make this particular die would start with planing up the die 
block, stripper, and punch plate. 

Placing Holes. If the piercing punches BB in Fig. 341, Tool- 
Making, Part III, were, say, 1 inch in diameter, it is obvious that 
the punch holes in the punch plate and the die holes in the die must 
be exactly in line, as a large punch will not spring into the die as is 
the case with punches of small diameter. Therefore, the best way 
to make these holes in line would be to dowel the stripper to the die 
face and dowel the punch plate to the stripper, then lay out the 
holes by means of a height gage, and indicate the center mark on 
the punch plate true by clamping the die block containing the 
stripper and the punch plate to the faceplate of a lathe. Then spot 
the punch plate with a V-spotting tool held in the tool post, and 
drill, and bore the punch plate and stripper to the desired diameters. 
Remove the punch plate and stripper and bore the larger recess in 
the die for bushing. The die must be clamped to the faceplate in 
such a mannet that the punch plate and stripper can be removed 
without disturbing the location of the die on the faceplate. Very 
accurate results can be obtained in this manner, providing the holes 
are bored after drilling. 

A more accurate method of locating the holes is to attach the 
punch plate and stripper to the die, then lay out approximately the 
location of the holes on the rear side of the punch plate. A small 


DIES AND METAL STAMPING 


47 


hole is drilled and tapped say for a No. 10—32 screw in the center 
of the approximate location for the holes. Buttons that are faced 
on one end at right angles with their sides and that have a hole, say, 






Fig. 38. Diagrams Showing the Die, Stripper, and Punch Plate 


| inch larger than a No. 10 screw are now attached to the punch 
plate, as fully described in Tool-Making, Part II, Figs. 268 and 269. 
The object in using the button method is that the die-maker is 
enabled to measure with micrometers from outside to outside of 
buttons and can place the buttons to within a tenth of a thousandth. 





























48 


DIES AND METAL STAMPING 


When the die is removed from the lathe faceplate, the die, 
stripper, and punch plate are in the condition shown in Fig. 38. 
The piercing dies are recessed as at a on the die block in Fig. 38, for 
the reason that the diameter of the hole is given in thousandths, and 
should the holes be bored a trifle too large, the die would be prac¬ 
tically ruined, otherwise. Also, it may be desired to change the 
diameter of the piercing dies, which can be readily accomplished by 
removing the bushings and inserting new ones having holes of the 

desired diameter. 

Referring to Fig. 38, 
it will be noted that 
the clearance-had been 
bored in the ends of the 
blanking die. All that 
remains to complete 
this die is to carefully 
mill out the web be¬ 
tween the two holes; or 
the web may be cut out 
using a hack saw, and 
the sides machined in a 
shaper which will insure 
good straight lines. The 
same precautions rela¬ 
tive to screw holes and 

Fig. 39 . Making Punches for Gang Dies hardening as already 

described must be fol¬ 
lowed out on all dies. The stripper is machined out in the same 




Cutting Off Tool 


J 


manner. 


Punches. The punch plate is set on the die, care being exer¬ 
cised that the proper side is placed against the die and that the punch 
holes line up approximately with the die holes. The outline of the 
die is now scribed on the punch holder in order to find the approxi¬ 
mate location of the blanking punch. The blanking punch is prefer¬ 
ably turned with a shank, and a hole is drilled and reamed through 
the punch plate for a tight fit on the punch shank. 

The piercing punches must be made, hardened, and ground, if 
necessary, and inserted in the punch plate before the blanking 































DIES AND METAL STAMPING 


49 


punch is made, for the piercing punches, being left somewhat longer 
than the blanking punch, are used as guides to positively locate the 
blanking punch over the blanking die. If the punches are to be 
ground, they can be turned upon centers, or can be made as in 
Fig. 39, and the piece that is held in the chuck is left on the punch 
and serves as a holding means when grinding. After the punches 
are ground, the soft end can be cut off as at b, Fig. 39. Punches 
made with a head are easier to make without centers, and, as the 



Fig. 40. Method of Holding Punches and Blanking Dies 


punch plate is attached to the punch holder as in Fig. 40, the punches 
cannot push out or pull out. 

Having inserted the piercing punches and the blanking punch in 
the punch plate, a dowel hole is now drilled and reamed lengthwise 
of the shank, as in Fig. 41. The hole should be drilled so that three- 
fourths of the diameter of the dowel pin is in the punch plate. A 
well fitting dowel pin is driven in this hole and the punch is ready 
to lay out. Upon entering the piercing punches in the piercing dies 
the face of the blanking punch comes in contact with the face of the 
die, in which position the outline of the die is scribed on the face of 
the punch. The blanking punch is now driven from the punch 
plate and milled to the line, beveled, and returned to the punch 




























































































































50 


DIES AND METAL STAMPING 


plate to start the first shear, being guided by the piercing punches 
which, being longer, of course enter before the blanking punch comes 
in contact with the plate. After the blanking punch has been forced 
in a short distance, the punch may be removed, or may be finished 
while in the punch plate, as suits the fancy. 

Pilot pins to enter the holes pierced in stock must be placed in 
the blanking punch and must be exactly the same center distance 
apart as the piercing dies, or else the holes will be distorted when 
blanking. In this particular die a thin disc 1 inch in diameter may 

be turned on the end of a 
rod held in a lathe chuck, 
and, at the same setting to 
insure concentricity, a hole 
drilled and bored to fit a 
standard drill. The disc is 
then severed from the bar 
and may be clamped to the 
face of the punch so that the 
edge of the disc is exactly in 
line, or even, with the end 
of the blanking punch. The 
drill, since it fits the hole, 
drills the holes very close 
to the exact distance from 
the ends and the side of the 
punch. These pilot holes 
must be drilled clear through 
the punch, as the pilots are driven out when grinding the punch. 
The pilots are made with a shoulder and tempered to a dark blue, and, 
when the punch and plate are assembled, they appear as in Fig. 42. 

Proper Sequence. The reason that the piercing punches are 
made and inserted first is that the piercing-punch holes were already 
in the punch plate, and, if the blanking punch were fitted to the die 
without the piercing punches being entered in the die, the piercing 
punches would not line up with the die. Whether the punch plate 
is bored at same time as the die, or not, the piercing-punch holes 
should be the first to be bored, and the punches should be used as 
guides. It is readily seen that to transfer the holes from the die to 



Dowel Hole 



Fig. 41. Method of Drilling Dowel Hole 




















DIES AND METAL STAMPING 


51 


the punch plate while the blanking punch is entered in the die means 
that the punch plate is some distance from the die, and to transfer 
the piercing holes would mean that the punch plate would have to 
be parallel with the die and that any transfer drill used would only 
be guided by a thin edge of the tapered piercing die—altogether 
making an unsatisfactory and unworkmanlike method, although this 
haphazard method is practiced by many so-called expert die-makers. 
When punches are located in this manner, it always happens that 
the punches do not quite line up and must be sprung over, if slender, 



and if too large in diameter to spring, the punch-plate stock surround¬ 
ing the punch is swaged in order to crowd the punch over. Always 
use that method which contains the least number of chances for 
error, for, besides distinguishing the expert, it saves time in the end. 

SHEARING DIES 

Two=Punch Principle. The cutting action of dies termed shear¬ 
ing dies is similar to the action of shears, from whence they derive 
the name. When in use one part is placed in the punch holder and 
is called the punch, while the other half is attached to the die shoe 

































































































52 


DIES AND METAL STAMPING 


and is called the die, although in reality both members are punches. 
Shearing dies in their simplest form are used to cut pieces from 




Upper H<=>lf~ 




Lower Half 

I'ig. 43. Punch and Die Which Cut the Stock Away Leaving Blank Temporarily on the Strip 


strips or bars, but the shearing or two-blade principle has been so 
elaborated upon that the most economical type of die is that employ¬ 
ing the two-punch principle. 





















































































































































































































DIES AND METAL STAMPING 


53 


Advantages. Fig. 43 shows a plain type of die employing the 
two-punch method, and it will be noted that the method of obtaining 
the blank is directly opposite to that when a punch and die is used. 
An ordinary punch and die cuts the blank from the strip, while the 
type shown in Fig. 43 cuts the stock away, leaving the blank tem¬ 
porarily on the strip. This has many advantages. The blank can 




Fig. 44. Two-Punch Die with Formed Ears on Finished Blank 

i 

be put through a number of bending, drawing, or forming opera¬ 
tions, and when finally completed the blank is severed from the 
strip by the shearing punch. This type of die also saves consider¬ 
able stock, as the margin on the edge and the web necessary between 
the blanks when using a blanking die is eliminated. Fig. 44 shows 
a side view of the same type, elaborated upon to the extent of form¬ 
ing several ears before severing the finished blank. 








































































54 


DIES AND METAL STAMPING 


Making Lower Punch. Strains. The first piece of the die in 
Fig. 43 to be made is lower punch a. It will be noted that the 
punch is not machined the same shape its entire height but that a 
supporting plate is left on the bottom. This plate or shoulder 
should be left on all punches that have long ears as bbb, for, without 
the plate, the ears would spread apart or spring together during 
the hardening process. 

Another precaution that should be taken when making either a 
blanking die or a punch having long slender ears, as in Fig. 43, is 
to machine the steel all over to remove the scale, then slowly heat to 
bright red, and pack in lime to insure slow cooling and also to prevent 



oxidation to a great extent. The object of annealing is to remove 
the strains in the steel. 

Laying Ont. Having machined all over and blued the surface 
of the block for the punch, center lines are scribed lengthwise or 
crosswise of the punch block. Referring to sketch Fig. 45, the first 
dimension at the right of the cross-center line is J inch, therefore, a 
cross-line is scribed f inch from the center line by means of either the 
height gage or surface gage, or by measuring with a scale and slid¬ 
ing a square along the block until the blade touches the scale. The 
block should now look as at a in Fig. 46. The next dimension to 
the right of this line is also f inch, so the operation is duplicated, 
and the die block looks as at b in Fig. 46. Starting at the cross¬ 
center line the shortest dimension at the left is 1J inches, c, Fig. 46, 
and when this line is scribed on the punch the If dimension line d, 
Fig. 46, also is scribed crosswise. Before going further, each space 


























DIES AND METAL STAMPING 


between cross-lines is carefully measured and checked with the 
dimensions on the sketch. The radius around the center hole calls 
for \ inch. Setting divider points | inch apart, the circle is scribed 
as at e , Fig. 46. The large radius calls for J inch, and is struck from 
a point If inches from the center and on the center line.' As we 
already have this location, the divider points are set j inch apart 
and a circle is scribed as at /, and from the same point the f-inch 
radius is scribed. Also from the same point there is scribed a J-inch 




> r 

4 . 


y! 


J u 

j 

L 

* 



Fig. 46. Layout of Punch on the Block 


circle h which is the width of the bar. Using a surface gage or a 
height gage the two lines ii are drawn on the punch block. The two 
f-inch radii jj are now scribed, completing the outline of punch. 
The j^-inch circle h for the hole is scribed, and the punch is ready 
to machine. 

Piercing Die . A small prickpunch mark should be made in the 
center of the circle for the hole, and a small drill, say a No. 50, that is 
well sharpened and which runs true when gripped in the drill-press 
chuck is first used to drill a hole say \ inch deep. The object in 
























56 


DIES AND METAL STAMPING 


using the small drill is that the tendency to climb out of the prick- 
punch mark is reduced to the minimum, then, when using a larger 
drill to size the hole, the point of the large drill is more apt to follow 
the small hole. 

To indicate a hole in a job of this character would be a false 
attempt at accuracy due to the fact that the outside of the punch 
will be machined to a line. If, however, the dimensions are in 
thousandths, then the hole should be indicated and bored, and the 
J-inch outside diameter e could be machined at the same setting 
while the punch is strapped to the faceplate of the lathe. To com¬ 
plete the outside diameter e in the lathe, however, would require a 
splining tool and that light chips be taken by sliding the carriage 
of the lathe back and forth. 

The sides of the lower half must be straight, for the lower half 
is used to shear the upper punch parts. 

Hardening. In hardening the lower part it should be placed in 
the furnace face down, and when dipped in the bath the face should 
be the first to enter and a slight up-and-down motion should be 
kept up until the punch is hardened. The base or flange should not 
be hardened. The object of keeping the punch in motion while in 
the bath is to prevent a crack or bulge which would take place if the 
punch were placed in the bath and held at one point. Where the 
water line comes on the punch there will invariably be a crack. 
A better way to heat a punch of this character is to heat it by immers¬ 
ing in a bath of red-hot lead. 

Surfacing. After hardening, the face of the punch should be 
ground to insure a good sharp cutting edge all around, w r hich is 
an aid when transferring the outline to the upper half. The back 
of the punch is now ground parallel with the face of the punch. 
This should be done by placing the face directly on the bed of a sur¬ 
face grinder and holding the punch to the bed with wax applied 
with a heated soldering iron. A suitable wax for this purpose 
consists of the following parts by weight: beeswax 7; resin 2; shoe¬ 
maker’s wax 1. It is obvious that, when two surfaces are to be 
parallel, great chances for errors are experienced in gripping the 
work in a vise, and, after machining one surface, in gripping the work 
again for machining the opposite side. Always work from one face 
to another when possible, and, if the work requires extreme accuracy 


DIES AND METAL STAMPING 


57 


as regards parallelism, a cast-iron plate or a piece of steel somewhat 
larger than the piece of work to be machined is waxed to the bed 
of the grinder or shaper and the surface made smooth and true by 
light cuts. 

We now have a temporary bed that is absolutely parallel with 
the line of travel of the shaper ram or the V-ways of the grinder. 
The piece of work is now in turn waxed to this temporary bed and 
one side of the work machined and all wax removed from the work 
and the face of the temporary bed, then the work is placed machined 
face down on the temporary bed, and the other side is machined. 
This temporary bed can be also applied to lathe work by strapping 
it to the faceplate of the lathe, and truing the surface as a temporary 
faceplate; then strapping the work to this temporary plate the 
surfaces can be properly machined. 

A magnetic chuck, a flat-topped box containing coils that 
become powerful magnets when current passes through them, is 
used extensively for holding flat work, but if the work is thin the 
wax should be used instead of the magnetic chuck, for the reason 
that the magnetic attraction is so great that a curved thin piece of 
work will be straightened against the face of the magnetic chuck, 
and if the surface of the work is ground or machined it is level until 
the current is turned off in the chuck and then instantly assumes its 
original curved state. 

Making Upper Punch. Transferring. The lower punch is now 
finished, and its outline must be transferred to the punches of the 
upper part of the die. The small piercing punch c, Fig. 43, is the 
first punch to be permanently located in the punch holder and is 
left as previously described, ^ inch longer than the larger trimming 
punches. The large blocks for the trimming punches are attached 
to the punch plate by screws, and while dowel holes are placed in 
the punch blocks, the dowels are not put in until after the punches 
are hardened. Having attached the upper punch blocks in place 
on the punch holder, the piercing punch is entered in the piercing 
die and the lower part is positioned so that its edge is parallel with 
the edge of the punch holder of the upper part. In this position the 
two parts are clamped, the outline of the lower punch is scribed on 
the face of the punches of the upper half, and the punch blocks 
then are removed from the punch holder. 


58 


DIES AND METAL STAMPING 



Machining. The face of a block is placed against the solid jaw 
of a shaper vise, and a rod, say of J-inch diameter, is placed between 
the movable vise jaw and the back of the punch. This insures the 
face of the punch being flat against the face of the solid jaw. If the 
rod were not used and the movable jaw should tilt slightly, as they 
invariably do, the work would be just as likely to lie flat against the 
movable jaw, which is then on an angle, as it would against the solid 
jaw, and the planed surface would not be at right angles with the 
face of the punch. By using a semicircular shaper tool the entire 
punch can be machined. For machining semicircles in the shaper, 
it is a good plan to turn up a disc, Fig. 47, and attach it to a tool 
for use in tool post. As the disc can be measured, it is much easier 
to obtain the proper radius by turning the disc than it is to file the 

radius tool accurately. 

After all the punches 
of the upper half have 
been machined to the 
outline, ithey are then 
reassembled on the punch 
holder and the exact out¬ 
line obtained by shearing. 
The object in leaving out 
the dowels until after the 
punches are finished and hardened is that, when milling or shaping 
to the line, too much stock might accidentally be removed, which 
would ruin the punch, but, as there is more or less play between 
the screw hole and screws, it is easy to move the punch over far 
enough to obtain a sheared outline over the entire contour. After 
shearing, say, inch deep, the punch should be returned to the 
shaper and the surplus stock carefully removed until the shaper 
tool just scratches the sheared part. This operation requires great 
care and the machine should be run slower than for ordinary work. 

Locating on Punch Holder. After smoothing and filing the 
punches with a fine file the punches are hardened and located on 
the punch holder, and, when firmly pressed against the lower punch, 
the screws are tightened in the punches of the upper half. The 
dowel holes are then transferred from punches to punch holder and 
the dowels inserted. The faces of the punches are ground by plac- 



-\ 

m\ ' 

j 

Ilk. "1 

milk 

!! 
! !li: 

k. ' !l 

!! h 

! ill! 

’’1 Hill T 

''ll | |lj 

i, ' ! ! 

.. 


Fig. 47. Lathe Tool for Machining Semicircles 































DIES AND METAL STAMPING 


59 



ing the back of the punch holder on the bed of the grinder. A stripper 
to work between the punches of the upper half is made of i-inch 
steel and is attached to 
the punch holder by screws 
surrounded by coil springs. 

The counterbored recesses 
in the punch holder are 
considerably deeper than 
the heads of the screws, 
so that as the stripper is 
pushed back the screw 
head can travel in the 
counterbored recess. 

DRAWING AND FORM= 

ING TYPES 

DRAWING DIES 

Finding Size of Blank. 

Drawing dies as a rule are 
very simple to make, as 
the majority of drawn work 
is round, which means 
lathe work. Assuming 
that dies for the drawn 
cup in Fig. 48 are to be 
made, the first step is to 
ascertain the diameter of 
the blank when in its flat 
state. The thickness of 
the walls or side of the cup 
determines the diameter 
of the blank. For in¬ 
stance, if the cup is to be 
punched from yg-inch 

stock, and the side walls and bottom must be ■£§ inch after being 
drawn to a cup, the easiest way—if a sample cup is submitted—is 
to cut a round flat blank from same kind of metal and of the same 



Fig. 4S. Cup to Be Made by Drawing Dies 













































































































































60 


DIES AND METAL STAMPING 


thickness and to keep reducing the diameter of the blank until it 
balances or weighs the same as the cup. Another way is to figure 
the area of the sides and of the bottom and to find the diameter of 
the blank having the same area. This latter method, however, is 
only approximately close, as the corners may be rounding in the 
cup making it difficult to figure. 

Types of Die. In making the cup in Fig. 48, there are the fol¬ 
lowing three types of forming dies that will produce it: (1) com¬ 
bination punch and die, 
Fig. 49, that punches out 
the blank and draws it to 
cup shape at one stroke 
in a single-action press; 

(2) combination blanking- 
and-drawing die, Fig. 50, 
for producing the cup in 
one stroke fitted to a 
double-action press; and 

(3) plain blanking die a, 
Fig. 51, and drawing die 
b, Fig. 51, which require 
two distinct operations, 
and this type of die can 
be used either in a single- 
or a double-action press. 

Making Combination 
Type. Blanking Punch . 
To make the die shown in 

Fig. 49. Combination Punch and Die for Making Fig. 49 the DUllch is 
Cup, Fig. 48 ° 1 

turned up on centers or 
may be made from the end of a bar held in a chuck. The size of the 
cup is 2f inches outside. This means that the drawing die a, Fig. 49, 
which is in the blanking punch must be 2.375 inches when finished. 
As the punch is apt to distort in hardening, and also in order to 
present a better wearing surface, there is a sufficient amount of 
stock left on the outside diameter for grinding to size after hard¬ 
ening, and when turning, the inside a is left a trifle smaller in order 
to grind. The amount to leave, depends upon the size of the job 


Blanking Punch 
Bnd Drawing Die 


































































DIES AND METAL STAMPING 


61 


at hand; in this case .015 inch or .020 inch would be ample. Care 
must be exercised when turning and grinding to have the inside 
and the outside concentric. The outside is ground to the desired 
diameter, using micrometers, and, to measure the inside, vernier 
calipers or inside micrometers are used. The corners of the draw¬ 
ing die must be ground rounding so they are concentric with the 
die, and the corners must be highly polished to prevent the metal 
dragging when changing 
from the flat state to the 
cup. 



Drawing Punch. The 
drawing punch b , Fig. 49, 
also must be ground to 
size, and care must be 
exercised that the punch 
is exactly the right diam¬ 
eter. If the drawing 
punch is left .002 inch 
larger in diameter than 
the die less double the 
thickness of stock, it would 
cause the stock to be com¬ 
pressed, which, in the 
drawing operation, would 
lengthen the cup. To 
save stock, the cup could 
be made the same height 
using a smaller diameter blank, but the walls of the cup would 
be reduced in thickness; this means, of course, that the difference 
between the drawing punch and the die must be less than the 
thickness of the stock. 

Operation Points. The points to be observed in drawing dies 
are: proper difference between the diameters of drawing punch and 
die; polished corners of punch and drawing die; and concentricity 



Fig. 50. Punch and Die of Combination Type 


of inside and outside of drawing die and blanking punch. 

Stock Wrinkling . The proper working of a properly made 
drawing punch and die depends upon the spring tension under 
stripper c, Fig. 49. If the tension is too great, the blank is held 
































































































62 


DIES AND METAL STAMPING 


Blonhing Punch 


(a) 


between the faces of the blanking punch and stripper which often 
causes breaks in the corner of the cups. Again, if tension is not 
enough, the stock when changing from a flat blank to a cup forces 
the stripper down, which causes a wider space, between the stripper 
and the punch than the thickness of stock. This is the cause of 

wrinkling of the edges of 
the cup as shown at a, 
Fig. 48. When wrinkles 
appear, increase the 
spring tension. Often¬ 
times the wrinkles over¬ 
lap each other making a 
. double thickness of stock 
•to be crowded between 
the punch and the die 
where there is an allow¬ 
ance for only one thick¬ 
ness. This doubling of 
stock prevents the cup 
from passing through the 
die and as the punch con¬ 
tinues downward the 
punch simply pushes the 
bottom out of cup. 

The making of dies 
as shown in Figs. 50 and 
51 is identical in opera¬ 
tion with the foregoing 
description and the 
same points must be 

Blanking and Drawing Punch and Dies 

Shown Separately observed. 



Blanhing Die 



Fig. 51. 


Irregular Drawing Dies 

Method of Making. Drawing dies for irregular shapes are 
seldom made to blank and draw at the same stroke, one reason 
being that the shape of the blank often has to be changed 
owing to variation in thickness and hardness of the stock to 
be drawn. 





































































































































DIES AND METAL STAMPING 


63 


To make a drawing die to produce the cup shown in Fig. 52 

requires about the same procedure as to make a blanking die, except 
that in the drawing die 

the sides or walls are 
perfectly straight. The 
first step also is to make 
the drawing die, for 
before the blanking die 
can be made, the shape 
of the blank will have 
to be found. 

Punch. The draw- Fi e- 52. Irregular Cup to Be Made by Drawing Die 

ing punch in Fig. 53 should be made first. Assuming that the 




Fig. 53. Punch and Die for Making Fig. 52 


























































































































































































































































































































































































































































64 


DIES AND METAL STAMPING 


punch has been machined to the overall size desired and has been 
blued on its face, we now lay out the outline on the face of the 
punch, and all lines on the punch face must be made from the 
same end and the same side. For instance, if the punch block in 
the rough state should not be parallel, and one line were scribed 



Fig. 54. Method of Outlining on Die Block 


lengthwise of the punch from one side, then another line were 
similarly scribed from the other side of the punch, the two lines 
scribed would not be parallel. The punch should be machined 
between centers either on a miller or on a shaper. 

The object in making the punch first is that its thickness and its 
length can be readily measured with micrometers, and when the 

punch is finished its out¬ 
line may be scribed on 
the die, then parallel 
lines may be scribed 
around this punch out¬ 
line a distance apart 
from the outline equal 
to the thickness of 
stock. Fig. 54. 

Die. The die outline is obtained by finding the radial centers 
of the circular punch outlines on the die, and scribing with dividers 
set as much larger as the thickness of stock, as at a , Fig. 54, then 
scribing the connecting straight .lines. After machining the die 
nearly to the lines the punch should be used as a guide. By placing 



Cut From a 

Fig. 55. Method of Determining Proper Size of Die 































































































DIES AND METAL STAMPING 


65 


the punch in the die, a piece of strip steel the same thickness as the 
stock to be used is inserted on each side between the punch and the 
die at the straight portion of the outline. For determining when the 
die is sufficiently larger a semicircular piece, Fig. 55, can be used; the 
semicircular piece being made by boring a hole in a piece of soft steel 
or brass the same diameter as twice the radius of the punch and turn¬ 
ing the outside of the steel to a diameter of the desired die radius. 

When sharp corners appear in the cup to be drawn, the die 
must have well rounded corners at the top gradually tapering to a 
sharp corner. If the cup to be drawn is of some depth, then two or 
more drawing dies are necessary. In this connection the draws 
are referred to as first, second, etc., and final. The first draw merely 
starts the cup to approximate shape, while the next draw makes the 
cup somewhat closer to finished shape, and the final draw completes 
the shape. Spring pads are used on practically all drawing dies. 

FORMING DIES 

Method of Making. Forming dies, while very simple in design 
and to make, often present difficulties, inasmuch as the metal being 
formed does not always form up to just the shape of the die or the 
desired shape. The forming punch and die can be made exactly the 
shape desired in the blank but the metal may crawl —the shop phrase 
for metal going where it is not intended to go—or the temper of the 
metal may play an important part, and even after the forming punch 
and die are made to produce the desired blanks the next shipment 
of metal may be of a different temper and the die must be altered. 

There are no hard and fast rules to lay down for forming dies, 
except to allow for the double thickness of stock between the punch 
and the die. The making of forming dies is a cut-and-try method. 
One point must be borne in mind—if dies to produce a formed piece 
are to be made, the forming punch and die should be made first in 
order to determine the exact shape of the blank from which the 
blanking die is made. 

EMBOSSING DIES 

Embossing. Embossing means to raise a figure, or design, 
above the flat surface of sheet stock. In operation the best results 
are obtained from the blow by attaching the force, or punch, or 
male member of the die to the hammer of a drop press. 


66 DIES AND METAL STAMPING 

Die Sinking. There are three methods of making embossing 
dies, and to employ any of the methods the workman must be an 
artist, for the outline of the design must be transferred from a sketch 
or possibly from a sample to the face of the die—if the design is of 
a floral or landscape effect, it means freehand sketching to obtain 
the desired outlines on the die face. Embossing dies proper, as well 
as drop-forging dies, are distinctly apart from the work expected of 
tool-makers or blanking die-makers, and embossing die-makers are 
known as die-sinkers. 

Robbing Methods. The method most generally used is known 
as the hobbing method. A male member or hob is made, as in 
Fig. 56, which is for a suspender buckle, and when finished the hob 
is hardened and forced into the face of the die block. This operation 

can be done either (1) 
cold, using hydraulic 
pressure, or (2) a flat-face 
punch can be attached 
to the hammer of a drop 
press, the die block 
heated to a bright red 
and placed in the drop 
press, and the hob placed 
in position on the face of 
the die block, the ham¬ 
mer then being allowed to fall, and forcing the hob into the hot die. 

When the latter method is used, however, the design as forced 
into the die block is rough, due to oxide scale from heating and 
cooling the die block. Also there is J-incli shrinkage per foot to 
molten steel, and the shrinkage of steel when only red hot is con¬ 
siderable. However, the rough design is in the die block, and 
with semicircular, diamond-point, and flat engraving tools the figure 
is finished and smoothed with die-sinkers’ files called rifflers. The 
final polish necessary in an embossing die is obtained by using 
the end of a small stick of wood and loose emery; every part 
of the design in the die must be free from scratches, for any mark 
in the die will be transferred to the work. 

Reverse Cutting. The third method is to cut the design directly in 
face of the die block. To do this the die-sinker must cut the design 






















































































DIES AND METAL STAMPING 


67 


the reverse of that desired, which is the most difficult method. Wax 
is used to obtain the impression. The surface of the die block or 
impression is smoked with a match to prevent the wax sticking and 
when the wax is forced into the impression in the die the wax shows 




Fig. 57. Embossing Dies Used for Jewelry Work 


the design and is the die-sinker’s guide. The force or punch is made 
by shaping its end to practically the same outline as the depression 
in the die, and by forcing it cold into the die by hydraulic pressure, 
or the die may be fastened to the bed of a drop press and the force 
attached to the hammer and forced into the die, either hot or cold. 




































































































































68 


DIES AND METAL STAMPING 


After a complete impression has been transferred from the die to 
the force the design on the force must be made smaller than the die 
to allow room between force and die for the stock to be embossed. 

Jewelry Dies. Fig. 57 shows another style of embossing die 
which is used extensively for finger rings, breastpins, etc. The die 
shown is for a ring, and in operation the piece of gold is placed over 
the design in the die and a flat punch strikes the gold, forcing the 
design in on one side only. The piece of gold is then trimmed in a 
punch and die called a trimming die, which is nothing more nor less 
than a plain blanking die. 

FLUID DIES 

Usage. There are many articles that can be formed by filling 
a cup with soapy water, placing the cup in a die, and allowing a 
punch—preferably in a drop hammer—to strike the contained 
water and to force the metal of the cup into the design of the die. 
Door knobs, watch cases, and umbrella handles are of the class of 
work that can be done profitably with fluid dies. 

A power press is not suitable for forming with water as water 
will not compress and the travel of the press is so slow that, unless a 
perfect fit is made between the punch and the die, the water escapes 
and there is not pressure enough to force the metal. On the other 
hand, if a perfect fit is made between the punch and the die, the 
water acts as a solid mass, and the crank shaft of the press would be 
sprung, if not broken. Water for forming or embossing is only used 
when the forming takes place on the side of the cup, as shown in the 
pieces in Fig. 58. Any design or shape on the end of the cup could 
of course be done in a plain die and struck with a punch. 

Operation of Fluid Die. Water forming dies, Fig. 59, are made 
in halves, one half stationary and the other movable, so that work 
can be removed after forming. Referring to a, Fig. 58, which is an 
umbrella top, it requires a cup formed as at e, Fig. 58, prior to form¬ 
ing in the fluid die. In operation a quantity of these cups in their 
plain state are placed in a pail of soapy water, the operator by mov¬ 
ing the lever, a, Fig. 59, opens the fluid die, and, as a cup when 
removed from the pail is full of water, the cup is carefully placed in 
the die so as not to spill the water, and the die is closed. Generally 
a locking device is attached to the die to prevent its flying open 
when the punch strikes the water. 


DIES AND METAL STAMPING 


G9 


Hammer 13 low, Ihe height of fall of the hammer containing 
the punch must be determined by experiments on each type of 
blank. When the proper height is found that will give the full 
design on the cup, the press hammer is set so that the fall will be 
uniform for each blank. The hammer must also be a perfect fit 



(f) (9) 


Fig. 58. Examples of Work Done by Fluid Dies 


between the uprights or ways of the drop press, for the punch must 
fit the upper opening in the die to prevent the escape of water, and 
a loose hammer would cause the punch to strike on the corner of 
the die, not only breaking the corner and the punch, but preventing 
the full blow on the cup. Also it is dangerous to the operator, as 

































































































































70 


DIES AND METAL STAMPING 


tlie small pieces that break from punch and die travel at tremen¬ 
dous speed. 

It is noted that the design is cut in the die shown in Fig. 59, but 
this is not essential as the design can be rolled in the plain blank and 
the height or blow of hammer regulated so that the swell or enlarged 
diameter on the blank can be obtained without marring the design. 

Substitute Processes.' Use of Rubber Core . The piece shown 
at b, Fig. 58, is a handle, and to make this form a cup would require 

Long lever 



i 



Fig. 59. Method of Operating Fluid Die 


several redrawing operations and annealings before the cup was in 
the shape required for forcing in the design. A piece of tubing is 
cheaper, but as the tubing will not permit filling with water, work 
of this character having open ends is formed by placing a long bar 
of spring rubber in the cup after it is in the die. Rubber merely 
changes form but does not set, and when the punch strikes the rubber 
the rubber flows to the unsupported part of the tubing in the die 
which of course forces the tubing into the design in the die. The 
















































































































































































































DIES AND METAL STAMPING 


71 


rubber assumes its original shape as soon as pressure is relieved and 
it then is readily removed. 

Roller Dies. The pieces b or d, Fig. 58, could also be made by 
the rolling dies in Fig. 60. The arbor a that the cup or tubing is 
placed on is considerably smaller than the inside of the cup or tub¬ 
ing, to allow the removal of the finished part. The female roll b is 
attached to the cross-slide of the rolling lathe or the roll dies can be 
used in an ordinary lathe by gripping the male member a in the 



lathe chuck and the female roll in the tool post of the lathe. In 
operation the cup or tube is placed on the revolving roll in 
the chuck and the roll b is brought to bear against the work. The 
friction between the two rolls and the work is sufficient to cause the 
work to rotate, and as the cross-slide of the lathe is moved toward 
the center of the lathe the beading or form is transferred from the 

rolls to the work. 

Forming of Die* Locating Hole. When making fluid dies the 
two halves are machined exactly the same height, and the faces 







































































































72 


DIES AND METAL STAMPING 


that come in contact with each other when the dies are together 
must be at right angles with the bottom. The two pieces are either 
screwed to a plate or attached to a special holder so that one half 
can be removed and replaced and the plate strapped to the face¬ 
plate of a lathe. A fine prickpunch mark is placed exactly on the 
line where the two halves meet and the prickpunch mark should be 
in the center of the two halves. If the prickpunch mark is indi¬ 
cated true, the hole will have half its diameter in each half of the 
die block; otherwise, one half will be of a greater diameter and 
trouble will be experienced in removal of the formed cup. The 
stock is removed in the usual way by spotting with a flat spotting 
tool, Fig. 61, rigidly held in the tool post to insure the spot being 
true, as the spotting tool actually bores or turns the recess spot 
which is to be the starting point for the drill that removes the stock. 
The angle of the spotting tool and the drill should be the same. 



Drilling. Good results cannot be obtained by holding an ordi¬ 
nary drill in a chuck in the spindle of the tailstock of a lathe as there 
is too much spring due to play between the spindle and the hole of 
the tailstock, and due also to the spring of the drill, chuck jaws, 
and spindle of the tailstock, which is greatly increased as the dis¬ 
tance from the point of the drill to the tailstock is increased. A 
mark, or a piece of wire is placed on the drill the desired distance 
from the point of the drill to act as a guide for the depth to be drilled. 
If the drill is too large to enter the tailstock chuck, a dog may be fas¬ 
tened to the shank of the drill, using a thin piece of sheet brass between 
the drill and the dog to prevent marring the drill, and, by placing 
the center of the tailstock in the center of the drill and allowing the 
tail of the dog to bear on the seat of the tool post, the hole can be 
drilled. 

A tool should be fastened securely in the tool post of the lathe 
and the tail of the dog should just touch the tool when the center 







DIES AND METAL STAMPING 


73 


of the tailstock is bearing on the drill center, and as the drill is fed 
into the work the carriage of lathe should also be moved along at 
exactly the same rate of speed, always keeping the tail of the dog 
bearing against the tool and also bearing on the seat of the tool post. 
If this is not done, the drill is likely to draw in, especially so if the 
drill passes clear through the work, and, as the drill catches or 
draws in, the center of the drill is pulled away from the lathe center 
in the tailstock, and the drill then rotates with the work. The 
object of having the tail of the dog bearing against the tool in the 
tool post is to enable the die-maker to hold the drill on the center of 
the tailstock. Under no circumstances should the dog be held by 
hand, either when drilling, or when removing the drill, while the 
lathe is rotating. The pressure and blow of the tail of the dog when 
a 1-inch drill catches in the work is sufficient to crush a hand or 
to sever a finger. Many fingers are lost in this manner. 

It is appropriate to mention the danger when attempting to 
hold work by hand in drilling with a drill press. Always bolt the 
work to the table if the work is large or thin, or hold the work against 
a rigid stop on the drill-press table, and if the work is small it can 
be held in a large clamp or wrench. Thin work catches on a drill 
more often than heavy pieces, due to the point of the drill passing 
through the work before the body of the drill enters, and the work 
will run up the spiral of the drill to the end of the spiral, then rotate 
with drill. At times the work simply tilts at an angle and instantly 
assumes the same number of revolutions as the drill, and severe 
lacerations are the result if work is held by hand. The writer once 
had a f-inch drill catch in a drop-forge die block that weighed 112 
pounds and the block was whirled, nearly upsetting the drill press, 
and finally the drill broke and the block was hurled some distance 
from the press. Emphasize again the tool-makers’ slogan—“elimi¬ 
nate all chances”. 

Boring to Form. Having drilled the hole in the fluid die to 
proper depth, the form is now bored. This involves the use of a 
blanked piece of steel,/. Fig. 58, that was previously turned the exact 
shape desired or rather the shape of the desired cup. By using 
formed boring tools the impression in the die is made to absolutely 
fit piece / when the dies are closed. As the larger diameter of the 
die is blind, that is, cannot be seen when boring, the shape is deter- 


74 


DIES AND METAL STAMPING 


mined by placing an even light coating of Prussian blue on the 
- model piece / and rotating piece / when the die halves are bearing 
against it. A streak or streaks of blue will show in the die and by 
moving the movable half of the die the die-maker is enabled to see 
the work and to set the boring tool so that it will cut exactly on the 
streak of blue paint. This type of lathe work requires patience and 
skill, and several specially made boring tools of different radii. 

Forming until Cherry. Another way in which this type of die 
can be made is to bore the die as above, almost to size and shape, 
and to finish the die in a drill press by having the model / of tool 
steel with teeth cut in it, g, Fig. 58, as in a formed milling cutter. 
The formed cutter, which is called a cherry, is hardened, and is 
gripped in a drill-press chuck, and the dies closed on the cherry. 
As the cherry revolves, the two halves which are held between 
clamps are closed onto the cherry, which cuts the desired form. 
The drill press must be stopped frequently and the clamp removed 
and the chips cleaned from the cherry, as there is no chip 
escape; plenty of oil should be used. If the design of die is not 
too intricate, however, the lathe method is quicker and in most 
cases better. 

Cutting Design. Having obtained the desired shape in the die 
halves, the next operation is to cut the design. It is obvious that 
the hob method cannot be used in a die made in halves, as the design 
on a, Fig. 58, encircles the blank, and, if a hob were made having 
the design extending the entire circumference, the action of the hob 
when closing the two halves on it would be that the raised figures 
on the hob would cut away the die halves in a straight line. There¬ 
fore, the design must be cut in by hand, and the design must also 
be laid out in the die halves the reverse of that desired on the 
finished cup. 

Transferring. There are several methods employed in trans¬ 
ferring the outline of the design to the die. One method is to make 
a transferring roll, of material similar to printers’ rolls and of the 
same shape but a trifle smaller in diameter than the bored portion 
of the die. The roll has a central hole its entire length, and larger 
in diameter at the top. The design is now sketched on a piece of 
thin paper which is exactly the same length as the circumference of 
that portion of the die having the figures, and after the design is 


DIES AND METAL STAMPING 


75 


accepted the lines of the design are inked, using slow drying printer’s 
ink, and the paper strip is pressed into a straight piece of wood 
which has been grooved the same shape as the contour of the die 
and the composition roll, as in Fig. 62. By rotating the composition 
roll from one end of the paper to the other the ink is picked up on 
the roll. Then, by cleaning the die thoroughly and placing the 
composition roll in the die and forcing a round plug in the small hole 
in the composition roll, the roll is expanded to fit the die and the ink 
from the roll is transferred to the die. This method only gives the 
general design and its location, as the ink will spread somewhat. 
With an engraver’s point, which is a fine oil stone in the form of a 



Fig. 62. Rolling Die with Composition Roll 

lead pencil, or with a sharp scriber, the outline of the design is 
scratched in the die. 

Finishing. From now on the work is strictly die-sinking and 
engraving, using small curved cold chisels to remove the bulk of the 
steel, shaping with engraving tools of various shapes, and lastly 
smoothing with files and wood stick with emery. 

Die-sinker’s wax is used for proving, and by smoking the surface 
of the die and forcing in the wax the impression as it should be on 
the cup is formed in the wax. The wax should be examined closely 
to find if any portion of the figure of the design is distorted, for an 
undercut on any part of the design will prevent the cup from being 
removed after being forced into the die. 


















76 


DIES AND METAL STAMPING 


DROP=FORGING DIES 


Typical Operation. When the term drop-forging dies is used it 
is generally understood to mean forging dies for forming red-hot 
metal. In operation these are two die blocks—upper and lower— 
as in Fig. 63. The upper half contains one half of the impression 
and the lower block the other half of the impression. The upper 
half is keyed to the hammer or drop by means of the dovetail shank, 
and the lower block is similarly secured to the bed of the drop press. 



The impressions are so laid out that when one end and one side of 
each block are even the impressions are opposite. 

Breaking Down. At one side of the impression proper is another 
impression called the break down. A furnace nearby contains a 
number of bars of metal which are heated on one end to a bright 
forging red. The red-hot end is placed over the break-down impres¬ 
sion, and the drop is allowed to fall by tripping with a treadle. The 
blocks on coming together smash the heated bar into the break-down 








































































































































































































































































DIES AND METAL STAMPING 


77 


impression. The object of the break down is to allow the use of a 
smaller bar of metal and by being formed in the break down the shape 
of the heated end is formed and flattened so that there is metal 
enough to fill the impression proper. The instant the blocks come 
together there is a rebound and the treadle should be released to 
allow instant raising of the drop which is lifted by a board fastened 
to it at one end. The board passes between two revolving pulleys 
that grip it, and the hammer is raised by friction to a slight distance 
above an automatic stop or pawl, at which point the rolls separate 
and the drop rests on the pawl. 

Forming . The heated bar is now placed over the die proper, 
and enough blows are given the bar to fill the die completely. At 




Fig. G4. Drop Forging Showing Flash Attached and Flash Removed 


each stroke, however, the heated end should be raised from the die 
to allow the loose oxide or scale that may have formed to be blown 
or brushed from the lower die. Another reason for removing the 
bar a short distance from the die each stroke is to prevent heating 
the die unnecessarily. As there is generally more metal in the 
heated end than is necessary to fill the die, it is obvious that some 
of the metal will be forced out between the dies in a thin web- 
called the flash—a, Fig. 64. To permit the dies coming together 
and forming a piece to correct diameter, a recess, a, Fig. 63, is milled 
around the die for clearance for surplus metal or flash. There is a 
small connecting portion, b, Fig. 64, between the forged piece and the 
bar, called the sprue, which should be as small as possible. 











































78 


DIES AND METAL STAMPING 


Trimming. After the piece has been forged, it is then placed 
over a die having an open end to allow the passage of the sprue 
and called the trimming die, and the punch—being shaped to fit 
the forging to prevent its distortion—on descending, trims the 
flash from the forging and leaves the bar and forging as at c, Fig. 64. 

The sprue is then placed between two knives that are chisel¬ 
shaped punches fitted in an ordinary punch press, and the finished 
forging is severed from the bar. 

Methods for Saving Material. Tapering. If the work is of 
the type shown in Fig. 65, which is a bicycle crank having a large 
portion and tapering to a small end, the method of forg¬ 
ing is somewhat different—mostly to effect a saving in 
material. The rods are purchased a trifle larger than 
the largest diameter and cut to short lengths while cold 
in a large pair of power shears. These pieces are then 
heated to forging heat and forged tapering under a trip 
hammer, the hammer being fitted with two small blocks 
or dies with plain cylindrical impressions, and making 
several hundred blows per minute. By gripping the end 
of the rod in tongs the rod is worked back and forth 
while the hammer makes rapid blows on the work, which 
reduces or draws the stock to proper length and size. 
The success of this operation depends solely upon the 
skill of the operator, as the blows are so rapid and always 
at same point that if the operator fails to move the rod 

or turn it fast enough the work 
will not be round or tapered. In 
other words, the trip hammer 
produces the same work that a 
blacksmith would produce by 
hand hammering except in much quicker time. The forged piece is 
bent at right angles, then reheated, and afterward placed in a drop 
die for final shaping. 

Spreading. Fig. 66 shows another type of forging which is a 
sprocket wheel, and to produce this forging in one die would mean 
a tremendous loss of metal as the hub is so much thicker than the 
rim. If a thick piece of steel were placed over a center die and an 
attempt made to flatten the steel until it filled the die, it can be 



Fig. 65. Drop Forging with Tapered Stock 



































DIES AND METAL STAMPING 


79 


readily seen that, as the stock began to flow outward toward the 
rim of the die, it would flow in all directions, and the metal that 
would be forced into the spokes would be gradually pushed sidewise, 
or distorted. Therefore a smooth-face breaking-down die is used 
to form the hub and to spread the steel enough to completely cover 
the finishing die, after which the steel is reheated and final-formed 
in the finishing die. 

Shaping Die Block. Setting-Up. The first step in making 
drop dies is to select the die blocks; they must be large enough for 
the job, for the impression must not come too close to the edge of 



Fig. 66. Sprocket-Wheel Forging 




the blocks. A hole, say f inch in diameter, is drilled in each end of 
each block about \ inch deep and approximately central in the end. 
Then the block is placed, with its level surface down, on a planer 
bed, and with finger straps engaging the holes in the ends and prop¬ 
erly blocked up, as in Fig. 67; the die block is now brought to bear 
against a parallel strip that is parallel with the travel of the bed 
and that is clamped to the planer bed. The object of this parallel 
strip is that it not only aligns the edge of the die block with the 
travel of the planer bed but prevents the block from shifting when 
planing on the extreme edge, which is likely to happen as the block 




















SO 


DIES AND METAL STAMPING 


is clamped in the center by the fingers only. When a rough casting 
or forging is clamped to any machine bed or in any machine vise, 
it is good practice to place a thin piece of metal or cardboard between 
the clamped surfaces to prevent marring the machine surface. If 
the planer vise is large enough to hold the die block, there is of 
course no advantage in using finger straps and bolts, providing the 
solid vise jaw can be readily aligned with the travel of the bed. 

Forming Dovetailed Shank. Having secured the block to the 
planer, a cut is taken across the top, and, chalking or coppering the 



Fig. 67. Shaping Die Block for Drop Forging 


top, the width of the dovetail is scribed on the face. The stock is 
then planed away and the angle forming the dovetail is planed. 
Should the angle be 30 degrees from the vertical the head of the planer 
is set at 30 degrees by means of the graduated dial, and the flop 
which carries the tool should also be set way over in the same direc¬ 
tion that the head is swung, to prevent the tool gouging in on the 
back stroke. Some tool-makers lock the tool so that on the back 
stroke the tool drags in exactly the same line as on its forward or 
cutting stroke. This is not good practice, however, for the back 
drag causes more wear on the tool than the cutting or forward stroke. 















































































DIES AND METAL STAMPING 


81 


The dovetail shank is planed to fit a templet, and the angular 
sides must be smooth and straight, for any irregularity of surface 
prevents the long taper key from properly holding the block. For 
instance, should several ridges stand out on the angular sides of the 
shank due to uneven planing, the key would bear only on these 
ridges, and after a few blows when in the drop press the ridges 
would be likely to flatten, causing the key to become loose. The 
shoulders aa, Fig. 67, must be on a line; in order to obtain the best 
results, both sides are roughed nearly to the line, and the last chip 



is taken first on one side allowing the tool to start as close to the 
shank as possible and to feed out, then, without changing the ele¬ 
vation or position of tool, the head is moved over so that the tool is 
on the opposite side of the block, and a finish chip is taken. The 
angle sides are then roughed out, and the last chip should be light— 
a rigid keen cutting tool being used. 

For roughing out any heavy work the roughing tool a, Fig. 68, 
is best adapted. The diamond point should not be used for heavy 
cuts unless the cutting point is on a line with the tool face that the 
tool-post screw bears against. By referring to sketch b, Fig. 68, 
































82 


DIES AND METAL STAMPING 


which is a diamond-point tool, the cutting point is seen to be so 
far advanced from the line of tool support that any springing of the 
tool would cause it to dig in, as will be understood by noting the line 
showing the radius traveled by the tool point in springing. It will 
be noted that the lowest point of the radial line is below the line of 
the cutting surface. By using a roughing tool, as at c, Fig. 68, the 
springing tends to force the tool away or above the cutting line. 

Machining Top and Edges. Having fitted the shank to the 
templet, the straps can be removed and the die block fastened to 
the bed, shank down, and the edge of the shank brought to bear 
against the parallel strip. The top surface is machined sufficiently 
to obtain a true clean surface, and the final cut should be taken 
with a spiral finish tool, d, Fig. 68, for the top must have the die 
outline laid out on its surface, and a rough surface makes it difficult 
to see the scribed lines. The finishing tool when working is shown 
at e, Fig. 68. 

One top edge of the block is machined by using the down feed 
to a distance of, say, 1| inch on one side only. The block is then 
turned crosswise of the planer, and the top edge of one end is planed 
down the same distance. The machined edges of the end and side 
must be at right angles, for from these two machined surfaces—on 
both blocks—the dies are laid out, and the machined surfaces or 
edges are also used to set up the dies in the press by bringing the 
edges and ends in line with each other. 

Squaring. One way to square up the block so that the machined 
edge will be at right angles is the old-fashioned cut-and-try method 
—that is, to set the block as nearly as possible by using two squares, 
one against the cross-head of the planer, and the other along the 
machined edge of the block. After the first cut is taken down, a 
square is tryed on the block and the block is shifted a trifle, etc., 
until the end and the side are square—the shop term for being at 
right angles. This is a slow method, and a more workmanlike one 
is to clamp an indicator to the planer tool held in the tool post, 
allowing the pointer of the indicator to travel along the edge of the 
square blade while the base of the square is held against the side of 
the block. The pointer of the indicator will remain at the same 
point when the block is exactly square. 

Recessing of Die. Laying Old. After finishing the tops and 


DIES AND METAL STAMPING 


83 


the edges of both blocks the top surfaces of each are smoothed with 
emery cloth on a file. A center line is drawn lengthwise of each 
block by using a sliding-blade square as at Fig. 69 and a cross-center 
line is scribed also. Scribing the line on each block with the 




Fig. 69. Sliding-Blade Square Used for Laying Out 


same respective settings of the square—working from the end and 
side of each block, and scribing along the end of the blade of the 
square—insures the center of the cross-lines being the same on 
both blocks. 

Assuming that the die is to be laid out to produce the forging 
of the sprocket wheel shown in Fig. 66, the first move is to place a 


























































S4 


DIES AND METAL STAMPING 


fine prickpunch mark at the intersection of the lines on both blocks. 
As this particular forging is round, both blocks may be laid out 
exactly alike, but in the laying-out of forgings, such as Figs. 64 or 65, 
the outline of the forging must be laid out right and left, so that the 
outlines will match when the faces of the blocks are together. The 
center circle for the hub is scribed with dividers, as are also the 
circles for the rim, the inner diameter of rim, the circle for the diam¬ 
eter at the bottom of the teeth, and the outside diameter. The 


Fig. 70. Elevation of Die Block, Showing Shape of Lugs, Etc. 



spokes are now laid out at right angles with each other, using a 
sliding-blade square. 

If there is a dividing head on the milling machine or die-sinking 
machine, it is unnecessary to lay out the teeth, as a cutter of the 
right shape may be used and a tooth can be cut into the outside line, 
then the index shifted for the next tooth, etc. If it is necessary to 
cut the teeth by hand, then of course each tooth must be carefully 
laid out. 

Forming. The die block is fastened to lathe the faceplate, and 
the prickpunch mark is indicated true. The recess for the hub of 
the forging is turned in the block the proper depth and tapering. 
L T sually 5 degrees clearance is given on drop-die work of ordinary 
depth, and if the forging is somewhat deep, say 2 inches, 10 degrees is 
better; it is obvious that straight sides in the die would cause the 















DIES AND METAL STAMPING 


85 


metal to stick so that the red-hot bar would not be stiff enough to 
pry the forging from the die. The center lug a , Fig. 70, for forming the 
hole in the hub may be made solid or inserted, as suits shop practice. 
At the same setting the rim b and the flash clearance c are turned 
in the die. When turning the rim it is well to use a formed turning 
tool that gives the proper angle to the side of the rim and at same 
time shapes the bottom of the rim. 

The spokes are milled or cut in the shaper. The spokes and 
teeth can best be done on a die-sinking machine, which is a vertical 
milling machine having the dividing head on a table in the hori¬ 
zontal plane. 

Dies for forging sprockets and similar work are extremely 
simple to make as the work is mostly lathe work. The die for pro¬ 
ducing the monkey wrench, Fig. 63, and for the crank. Fig. 65, are 
also easy to make, as the die can be cut out in a shaper or a milling 
machine, except for the sharp corners which have to be chipped out 
by hand using a cold chisel and hammer. 

Completion of Die. Shrinkage Allowance. As steel in the 
molten state shrinks f inch per foot when cold, every dimension 
given on the blue print must be increased at the rate of J inch per 
foot to allow for shrinkage. For instance, if the finished diameter 
of the sprocket forging, in Fig. 66, called for 12 inches, the diameter 
of the corresponding recess on the die in Fig. 70 should be 12J inches, 
or if the diameter is 6 inches, then allowing for shrinkage the die 
must be 63 ^ inches, and if the forging is to be 3 inches the die must 
be inches, etc. There are shrink rules or scales on the market 
that instead of being 12 inches long are 12 J inches long, but the 
graduations are the same style as on an ordinary scale—in inches, 
from 1 to 12. In other words, the f-inch shrinkage allowance is 
taken care of by being evenly distributed throughout the 12J inches. 
All that is necessary, w r ith this scale is to set the dividers to, say, 
6 inches on it, and they are really set at 63 ^ standard inches. 

Matching. When making drop dies having round or tapered 
parts, as in Fig. 65, it is a good plan to turn up a piece of steel at the 
proper taper, or to the proper diameter if the work is straight, and 
to use this piece as a templet, with which, by placing an even thin 
coating of Prussian blue on the templet, the trueness of the recess in 
the die can be tested frequently. When both halves of the die are 



86 


DIES AND METAL STAMPING 


finished and the impressions are smoothed nicely, the blocks may be 
placed face to face, and, after slightly warming the blocks, the 
impression may be filled with molten babbitt. Babbitt does not 
shrink very much and the babbitt test piece may be examined to 
make sure that the impressions in each die match. Also the babbitt 
may be measured to check diameters and length. 

Hardening. The dies are hardened by being heated face down 
on a charcoal fire, and, when heated to a depth of several inches, 
by having a heavy stream of water played on the face of the die. 
Cast-iron dies may be used when only a few hundred forgings are 
required. 

Dies for Trimming. Trimming dies are usually made in halves 
to facilitate making, and are also frequently made of machine steel 
and casehardened as the forging is red hot when trimmed. If the 
forging is thin or light, the flash would cool so quickly that soft dies 
would be out of the question. The punch, however, can be case- 
hardened. 

The clearance on trimming dies varies from 5 degrees to 10 
degrees, according to the nature of the forging. In any case the 
forging must be able to pass through the die without being distorted. 
Trimming dies are open at one end to allow the sprue and rod to 
pass through, for the forging should stay on the rod as it often 
happens that the forging becomes distorted during trimming and it 
is necessary to strike it between the drop dies for final shaping of 
the forging. 


INDEX 





INDEX 


PART PAGE 

Bench micrometer_ I, 49 

Blanking and shearing die_II, 2 

alignment of stripper_II, 5 

die block, preparing_II, 8 

die shoe_II, 20 

die stock_II, 7 

finishing of die_II, 16 

forming of punch_II, 17 

gang dies_II, 44 

hardening of die_II, 15 

laying out die_II, 10 

laying out punch_II, 16 

making die bushing_II, 3 

making die shoe- II, 4 

sectional dies_II, 32 

shaping of die_II, 11 

shearing dies_II, 51 

size factor_II, 2 

binding_II, 3 

clearance_II, 2 

guiding_ II, 3 

resistance of sheets- II, 2 

sub-press dies_II, 20 

D 

Depth gage- I, 49 

Dies_ I, 13 

finishing_II, 16 

hardening- II, 15 

laying out_II, 10 

shaping_II, H 

Die block_H> 3 

Die bushing, making-II, 3 

Die-making and usage-II, 1 

Die shoe_II, 20 

Dies and sheet-metal stamping-II, 1-86 

Drawing dies_II, 59 

blank, finding size of- II, 59 

irregular_II, 52 

operation points_ II, 51 

types of-II, 50 

Drop-forging dies_H» ?5 

completion of die-II, 85 












































2 


INDEX 


Drop-forging dies (continued) part page 

operation_II, 76 

recessing of die_II, 82 

saving material_II, 78 

shaping die block_i-II, 79 

trimming die_ II, 86 

E 

Embossing dies_II, 65 

die sinking_II, 66 

jewelry dies_II, 68 

F 

Fluid dies_II, 68 

cutting design_II, 74 

forming of die_II, 71 

operation of_II, 68 

substitute processes_II, 70 

usage_ II, 68 

G 

Gages, types and design of_ I, 44 

depth_ I, 49 

limit_ I, 44 

micrometer_ I, 49 

plug- I, 46 

profile- I, 49 

receiving, making of_ I, 46 

snap- I, 45 

Gang dies_II, 44 

J 

Jigs and fixtures, design of_ I, 35 

design essentials_ I, 39 

drilling fixtures_ I, 35 

spring-pump locators_ I, 37 

V-type jig- I, 36 

jigs in general, design of_ I, 43 

rapid operation, devices for_ I ; 39 

drilling and reaming with same jig_ I, 41 

hinged covers_ I, 39 

indexing_ 1^ 41 

master plate_ 42 

multi-spindle operation_ I ; 49 

screw bushing_ 1^ 49 

slip bushing_ I ; 41 

sequence of operations, proper_ 33 

L 

Limit gage. I, 44 









































INDEX 


3 


PART PAGE 


Micrometer gages_ j 49 

P 

Plug gage--- i f 46 

Profile gage_____ i f 49 

Punches_, _ X, 13 

forming of___„_JI, 17 

layout-II, 16 

Punches and dies, design of___ I t 13 

blanking types___ l y 13 

combination_ I, 17 

piercing-and-blanking_ I, 13 

sub-press_ I, 16 

drawing and forming types_ I, 19 

blanking-and-drawing_ I, 20 

deep-drawing_ I, 26 

double-action_ I, 24 

drawing, simple_ I, 19 

embossing_ I, 30 

extruding_ I, 30 

fluid_ I, 34 

forming-*__ I, 31 

shaving_____'_ I, 27 

Punches and dies, types of_ I, 13 

R 

Receiving gage___ v _ I, 46 

Roller dies_II, 71 

S 

Screw-machine forming_,___ I, 6 

Sectional dies___._II, 32 

advantages_ II, 32 

attaching piercing punches - .. II, 41 

construction requirements...-..II, 34 

laying out ......-__II, 32 

making blanking punch -- II, 42 

making of die_II, 36 

shaping of die- II, 33 

Shearing dies_II, 51 

making lower punch_II, 54 

making upper punch.- II, 57 

two-punch principle..----II, 51 

Snap gage....--- I, 45 

Stripper__-.- - -.-..II, 19 

Sub-press dies_- — ..----II, 20 

assembling parts- II, 31 

fitting piercing punches and dies-----II, 28 












































4 


INDEX 


Sub-press dies (continued) part page 

making plunger_ II, 24 

making press body_II, 22 

making small parts_II, 25 

round holes, placing_II, 29 

special cutters, use of_ II, 27 

typical features_II, 20 

T 

Tool design_ I, 1-59 

gages_ I, 44 

jigs and fixtures_ I, 35 

punches and dies_ I, 13 

selection of type in_ I, 1 

successful process in_ I, 49 

accuracy, conditions for_ I, 55 

collaboration_ I, 58 

handling and machining methods_ 1,51,54 

observation_ I, 59 

outlining methods_ I, 56 

product design__ I, 57 

relation of operations, proper_ I, 49 

Tool types, selection in design of_ I, 1 

method, example of_ I, 1 

basis, production_ I, 1 

dies, relative advantages of_ I, 6 

drill jig, box_ I, 5 

milling fixtures_ I, 3 

turning, turret machine_ I, 6 

requisites of designer_ I, 13 

Trimming dies..„.II, 86 

































































































































































































































































































































